fix(ci): resolve SymbolCollision and Sessions CocoaPods dependencies for Firebase 13 (#16679)

FirebaseSessions/Tests/TestApp/Podfile

@@ -56,7 +56,7 @@ target 'AppQualityDevApp_CrashlyticsPerformance_iOS' do
 end
 
 target 'AppQualityDevApp_macOS' do
-  platform :macos, '10.15'
+  platform :macos, '11.0'
 
   # Comment the next line if you don't want to use dynamic frameworks
   use_frameworks!

SymbolCollisionTest/Podfile

@@ -48,7 +48,7 @@ target 'SymbolCollisionTest' do
     pod 'GooglePlaces', '> 8'
     pod 'GoogleSignIn', '> 6'
     pod 'GTMAppAuth'
-    pod 'GoogleTagManager', '>= 7.4.6'
+#    pod 'GoogleTagManager' # Incompatible with Firebase 13 (depends on FirebaseAnalytics < 12.0)
     pod 'GoogleToolboxForMac'
     pod 'GoogleUtilities'
 #    pod 'GTMHTTPFetcher' - conflicts with GTMSessionFetcher