github workflow: switch to JDK 11

Since Android Gradle plugin was updated, it now requires JDK 11.

Fixes:

> Could not resolve all files for configuration ':classpath'.
   > Could not resolve com.android.tools.build:gradle:7.4.0.
     Required by:
         project :
      > No matching variant of com.android.tools.build:gradle:7.4.0 was found. The consumer was configured to find a runtime of a library compatible with Java 8, packaged as a jar, and its dependencies declared externally, as well as attribute 'org.gradle.plugin.api-version' with value '7.6' but:
          - Variant 'apiElements' capability com.android.tools.build:gradle:7.4.0 declares a library, packaged as a jar, and its dependencies declared externally:
              - Incompatible because this component declares an API of a component compatible with Java 11 and the consumer needed a runtime of a component compatible with Java 8
              - Other compatible attribute:
                  - Doesn't say anything about org.gradle.plugin.api-version (required '7.6')

.github/workflows/build.yml

@@ -49,11 +49,10 @@ jobs:
         # If using the github runner 'macos-10.15'
         # $VM_ASSETS/select-xamarin-sdk-v2.sh --mono=6.12 --android=11.2
 
-    - name: Switch to JDK-8
-      if: ${{ false }} # Not needed, we stay with the default installed JDK
+    - name: Switch to JDK-11
       uses: actions/setup-java@v3
       with:
-        java-version: '8'
+        java-version: '11'
         distribution: 'temurin'
 
     - name: Display java version
@@ -177,11 +176,10 @@ jobs:
         sudo apt install -y ./xamarin.android-oss/*.deb &&
         echo "$HOME/xamarin.android-oss/bin/Release/bin" >> $GITHUB_PATH
 
-    - name: Switch to JDK-8
-      if: ${{ false }} # Not needed, we stay with the default installed JDK
+    - name: Switch to JDK-11
       uses: actions/setup-java@v3
       with:
-        java-version: '8'
+        java-version: '11'
         distribution: 'temurin'
 
     - name: Display java version
@@ -279,6 +277,15 @@ jobs:
       # If we want to also have nmake, use this instead
       #uses: ilammy/msvc-dev-cmd@v1
 
+    - name: Switch to JDK-11
+      uses: actions/setup-java@v3
+      with:
+        java-version: '11'
+        distribution: 'temurin'
+
+    - name: Display java version
+      run: java -version
+
     # Some components of Keepass2Android currently target android API 26 which are not available on the runner
     - name: Download android-26 API
       shell: cmd