Fix ProGuard issue with javax.xml.namespace.QName; update AGP (bitfireAT/davx5#512)

* Update to AGP 8.2.1
* Add keep rule for javax.xml.namespace.QName

See #511
Closes bitfireAT/davx5#499

app/proguard-rules-release.pro

@@ -22,6 +22,9 @@
 # DAVx⁵ + libs
 -keep class at.bitfire.** { *; }       # all DAVx⁵ code is required
 
+# AGP 8.2 and 8.3 seem to remove this class, but ezvcard.io uses it. See https://github.com/bitfireAT/davx5/issues/499
+-keep class javax.xml.namespace.QName { *; }
+
 # we use enum classes (https://www.guardsquare.com/en/products/proguard/manual/examples#enumerations)
 -keepclassmembers,allowoptimization enum * {
     public static **[] values();

build.gradle

@@ -34,7 +34,7 @@ buildscript {
     }
 
     dependencies {
-        classpath 'com.android.tools.build:gradle:8.1.4'    // 8.2.0 seems to be broken, see https://github.com/bitfireAT/davx5-ose/issues/511
+        classpath 'com.android.tools.build:gradle:8.2.1'
         classpath "com.google.dagger:hilt-android-gradle-plugin:${versions.hilt}"
         classpath "com.mikepenz.aboutlibraries.plugin:aboutlibraries-plugin:${versions.aboutLibraries}"
         classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:${versions.kotlin}"