Bump dav4jvm from f2078bc846 to 2.1.2

Bumps dav4jvm from f2078bc846 to 2.1.2.

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

app/build.gradle

@@ -152,7 +152,7 @@ dependencies {
     implementation "android.arch.work:work-rxjava2:${workVersion}"
     implementation 'com.google.android:flexbox:1.1.0'
     androidTestImplementation "android.arch.work:work-testing:${workVersion}"
-    implementation ('com.gitlab.bitfireAT:dav4jvm:f2078bc846', {
+    implementation ('com.gitlab.bitfireAT:dav4jvm:2.1.2', {
         exclude group: 'org.ogce', module: 'xpp3'	// Android comes with its own XmlPullParser
     })
     implementation 'org.conscrypt:conscrypt-android:2.2.1'