Application not syncing when adding AdMob dependencies - firebase

Question

Hello I am new to android and I am having an issue syncing my app when trying to add the dependencies for the the admob the following error appears:
'''
In project 'app' a resolved Google Play services library dependency depends on another at an exact version (e.g. "[18.0.
2]", but isn't being resolved to that version. Behavior exhibited by the library will be unknown.
Dependency failing: com.google.android.gms:play-services-measurement-api:18.0.2 -> com.google.android.gms:play-services-
measurement-sdk-api#[18.0.2], but play-services-measurement-sdk-api version was 18.0.3.
The following dependencies are project dependencies that are direct or have transitive dependencies that lead to the art
ifact with the issue.
-- Project 'app' depends onto com.google.firebase:firebase-bom#{strictly 26.8.0}
-- Project 'app' depends onto com.google.android.gms:play-services-ads-lite#{strictly 20.6.0}
-- Project 'app' depends onto com.google.android.gms:play-services-measurement-sdk-api#{strictly 18.0.3}
-- Project 'app' depends onto com.google.firebase:firebase-bom#26.8.0
-- Project 'app' depends onto com.google.android.gms:play-services-measurement-api#{strictly 18.0.2}
-- Project 'app' depends onto com.google.android.gms:play-services-ads#{strictly 20.6.0}
-- Project 'app' depends onto com.google.android.gms:play-services-ads#20.6.0
-- Project 'app' depends onto com.google.firebase:firebase-analytics#{strictly 18.0.2}
-- Project 'app' depends onto com.google.android.gms:play-services-ads-lite#20.6.0
For extended debugging info execute Gradle from the command line with ./gradlew --info :app:assembleDebug to see the dep
endency paths to the artifact. This error message came from the google-services Gradle plugin, report issues at https://
github.com/google/play-services-plugins and disable by adding "googleServices { disableVersionCheck = true }" to your bu
ild.gradle file.
'''
the following is the build.gradle file :
plugins {
id 'com.android.application'
id 'com.google.gms.google-services'
}
apply plugin: 'kotlin-android'
apply plugin: 'com.android.application'
apply plugin: 'com.google.gms.google-services'
android {
compileSdkVersion 29
buildToolsVersion "30.0.2"
defaultConfig {
applicationId "rubydev.learningforkids"
minSdkVersion 21
targetSdkVersion 29
versionCode 1
versionName "1.0"
testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
}
buildTypes {
release {
minifyEnabled false
proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
}
}
compileOptions {
sourceCompatibility JavaVersion.VERSION_1_8
targetCompatibility JavaVersion.VERSION_1_8
}
}
dependencies {
implementation 'androidx.appcompat:appcompat:1.2.0'
implementation 'com.google.android.material:material:1.2.1'
implementation 'androidx.constraintlayout:constraintlayout:2.0.4'
implementation 'androidx.work:work-runtime:2.3.4'
implementation 'androidx.legacy:legacy-support-v4:1.0.0'
implementation 'androidx.recyclerview:recyclerview:1.1.0'
implementation 'com.google.firebase:firebase-auth:20.0.3'
implementation 'com.google.firebase:firebase-firestore:22.1.2'
implementation 'com.google.firebase:firebase-storage:19.2.2'
implementation 'androidx.lifecycle:lifecycle-livedata-ktx:2.2.0'
implementation 'androidx.lifecycle:lifecycle-viewmodel-ktx:2.2.0'
implementation 'androidx.navigation:navigation-fragment:2.3.3'
implementation 'androidx.navigation:navigation-ui:2.3.3'
implementation 'com.google.android.gms:play-services-ads-lite:20.6.0'
testImplementation 'junit:junit:4.+'
androidTestImplementation 'androidx.test.ext:junit:1.1.2'
androidTestImplementation 'androidx.test.espresso:espresso-core:3.3.0'
implementation platform('com.google.firebase:firebase-bom:26.8.0')
implementation 'com.google.firebase:firebase-analytics'
implementation "androidx.core:core-ktx:1.6.0"
implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlin_version"
implementation 'com.google.android.material:material:1.1.0-alpha10'
implementation 'com.thebluealliance:spectrum:0.7.1'
implementation 'com.squareup.picasso:picasso:2.71828'
implementation 'com.tomer:fadingtextview:2.6'
implementation 'pl.droidsonroids.gif:android-gif-drawable:1.2.19'
implementation 'de.hdodenhof:circleimageview:3.0.0'
implementation 'com.google.android.material:material:1.3.0-alpha03'
implementation 'com.github.dhaval2404:imagepicker:2.1'
implementation 'com.github.lzyzsd:circleprogress:1.2.1'
implementation 'net.danlew:android.joda:2.10.9.1'
implementation 'io.github.pilgr:paperdb:2.7.1'
implementation 'com.google.android.gms:play-services-ads:20.6.0'
implementation 'com.google.android.ads.consent:consent-library:1.0.6'
implementation 'com.firebaseui:firebase-ui-auth:4.2.0'
}
repositories {
mavenCentral()
}