Bump firebase-messaging from 17.6.0 to 18.0.0 (#1347)

Bumps firebase-messaging from 17.6.0 to 18.0.0.

Signed-off-by: dependabot[bot] <support@dependabot.com>

Bump minSdkVersion to 16

Signed-off-by: mueller-ma <mueller-ma@users.noreply.github.com>

mobile/build.gradle

@@ -28,7 +28,7 @@ android {
 
     defaultConfig {
         applicationId "org.openhab.habdroid"
-        minSdkVersion 14
+        minSdkVersion 16
         targetSdkVersion 27
         versionCode 143
         versionName "2.7.3-beta"
@@ -117,7 +117,7 @@ dependencies {
     fossImplementation 'org.osmdroid:osmdroid-android:6.1.0'
 
     // FCM
-    fullImplementation 'com.google.firebase:firebase-messaging:17.6.0'
+    fullImplementation 'com.google.firebase:firebase-messaging:18.0.0'
 
     // About screen
     implementation 'com.github.daniel-stoneuk:material-about-library:2.4.2'