fix: Restore support for Android 5-7

app/build.gradle

@@ -29,7 +29,7 @@ android {
 
     defaultConfig {
         applicationId "tech.relaycorp.ping"
-        minSdkVersion 26
+        minSdkVersion 21
         targetSdkVersion 30
         versionCode 7
         versionName project.findProperty("versionName") ?: "0.7"
@@ -68,8 +68,7 @@ android {
         }
     }
     compileOptions {
-        // Workaround for https://github.com/relaycorp/awala-ping-android/issues/39
-        // coreLibraryDesugaringEnabled true
+         coreLibraryDesugaringEnabled true
 
         sourceCompatibility = JavaVersion.VERSION_1_8
         targetCompatibility = JavaVersion.VERSION_1_8

app/firebase-test-lab.yml

@@ -4,18 +4,17 @@ spec:
   test: app/build/outputs/apk/androidTest/debug/app-debug-androidTest.apk
   timeout: 30m
   device:
-# TODO: Test on Android API < 26 once we restore support for it.
-#    # Asus Nexus 7 (physical). The oldest device we're testing.
-#    - model: flo
-#      version: 21   # Android 5.0
-#      locale: en
-#      orientation: portrait
-#
-#    # Nexus 5X (virtual)
-#    - model: Nexus5X
-#      version: 24   # Android 7.0
-#      locale: en
-#      orientation: portrait
+    # Asus Nexus 7 (physical). The oldest device we're testing.
+    - model: flo
+      version: 21   # Android 5.0
+      locale: en
+      orientation: portrait
+
+    # Nexus 5X (virtual)
+    - model: Nexus5X
+      version: 24   # Android 7.0
+      locale: en
+      orientation: portrait
 
     # Nexus 5X (virtual)
     - model: Nexus5X

app/lint.xml

@@ -10,7 +10,4 @@
     <issue id="SelectableText" severity="ignore" />
     <issue id="UnusedIds" severity="informational" />
     <issue id="UnusedResources" severity="informational" />
-
-    <!-- TODO: Remove once we restore support for Android API < 26 -->
-    <issue id="ObsoleteSdkInt" severity="informational" />
 </lint>

build.gradle

@@ -14,7 +14,7 @@ buildscript {
     }
   }
   dependencies {
-    classpath 'com.android.tools.build:gradle:4.2.2'
+    classpath 'com.android.tools.build:gradle:7.0.0'
     classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlinVersion"
     classpath "com.mikepenz.aboutlibraries.plugin:aboutlibraries-plugin:$aboutLibrariesVersion"
   }

gradle/wrapper/gradle-wrapper.properties

@@ -1,5 +1,5 @@
 distributionBase=GRADLE_USER_HOME
 distributionPath=wrapper/dists
-distributionUrl=https\://services.gradle.org/distributions/gradle-6.8.3-bin.zip
+distributionUrl=https\://services.gradle.org/distributions/gradle-7.0.2-bin.zip
 zipStoreBase=GRADLE_USER_HOME
 zipStorePath=wrapper/dists