Bump a-c dependency to 4.0.0

This is the latest currently-released version of android-components.
In the future we may consider using the -SNAPSHOT variant (essentially, a nightly version)
to keep up with the latest changes in a-c.

versions.gradle

@@ -25,7 +25,7 @@ def versions = [:]
 // GeckoView versions can be found here:
 // https://maven.mozilla.org/?prefix=maven2/org/mozilla/geckoview/
 versions.gecko_view = "70.0.20190710094220"
-versions.android_components = "0.52.0"
+versions.android_components = "4.0.0"
 versions.mozilla_speech = "1.0.6"
 versions.openwnn = "1.3.7"
 versions.google_vr = "1.190.0"