Use JDK11 and Gradle 6.7.1 in Android container

Signed-off-by: tobiasKaminsky <tobias@kaminsky.me>

.drone.yml

@@ -5,7 +5,7 @@ name: tests-stable
 
 steps:
   - name: gplay
-    image: nextcloudci/android8:android-60
+    image: nextcloudci/android8:android-61
     privileged: true
     environment:
       LOG_USERNAME:
@@ -87,7 +87,7 @@ name: tests-master
 
 steps:
   - name: gplay
-    image: nextcloudci/android8:android-60
+    image: nextcloudci/android8:android-61
     privileged: true
     environment:
       LOG_USERNAME:
@@ -170,7 +170,7 @@ name: analysis
 
 steps:
   - name: analysis
-    image: nextcloudci/android8:android-60
+    image: nextcloudci/android8:android-61
     environment:
       GIT_USERNAME:
         from_secret: GIT_USERNAME