Bump minimum Android SDK level to 23

.github/workflows/ci.yml

@@ -56,7 +56,7 @@ jobs:
         uses: android-actions/setup-android@v3
       - name: Install Android SDK
         run: |
-          sdkmanager "platforms;android-21"
+          sdkmanager "platforms;android-23"
 
       # Testing
       - name: Gradle Check

build-logic/src/main/groovy/org.igniterealtime.smack.android-conventions.gradle

@@ -3,7 +3,7 @@ plugins {
 	id 'org.igniterealtime.smack.global-conventions'
 }
 dependencies {
-	signature "net.sf.androidscents.signature:android-api-level-${smackMinAndroidSdk}:5.0.1_r2@signature"
+	signature "net.sf.androidscents.signature:android-api-level-${smackMinAndroidSdk}:6.0_r3@signature"
 }
 animalsniffer {
 	sourceSets = [sourceSets.main]

build-logic/src/main/groovy/org.igniterealtime.smack.global-conventions.gradle

@@ -1,7 +1,7 @@
 ext {
 	javaVersion = JavaVersion.VERSION_11
 	javaMajor = javaVersion.getMajorVersion()
-	smackMinAndroidSdk = 21
+	smackMinAndroidSdk = 23
 
 	androidBootClasspath = { getAndroidRuntimeJar() }
 }

smack-android/src/main/java/org/jivesoftware/smack/android/AndroidSmackInitializer.java

@@ -37,6 +37,8 @@ import org.minidns.dnsserverlookup.android21.AndroidUsingLinkProperties;
 public class AndroidSmackInitializer implements SmackInitializer {
 
     @Override
+    // Android deprecated StrictHostnameVerifier in API level 22
+    @SuppressWarnings("deprecation")
     public List<Exception> initialize() {
         SmackConfiguration.setDefaultHostnameVerifier(new StrictHostnameVerifier());
         Base64.setEncoder(AndroidBase64Encoder.INSTANCE);