Added build platform steps of the example to detect configuration issues (#620)

* Added CI step to build the example for Android and iOS (to proactively detect any issues)
* Upgraded Android build tools (for example)

Author: awhitford

.github/workflows/main.yml

@@ -40,6 +40,13 @@ jobs:
           flutter format --dry-run --set-exit-if-changed .
           flutter analyze --no-pub
           flutter test --no-pub --coverage
+
+      - name: Build Example
+        run: |
+          pushd example
+          flutter build appbundle --no-pub --debug
+          flutter build ios --no-pub --debug --no-codesign
+
       - name: Upload coverage to Codecov
         if: ${{ matrix.channel == 'stable' }}
         uses: codecov/codecov-action@v1

example/android/build.gradle

@@ -6,7 +6,7 @@ buildscript {
     }
 
     dependencies {
-        classpath 'com.android.tools.build:gradle:3.5.0'
+        classpath 'com.android.tools.build:gradle:4.1.1'
         classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
     }
 }

example/android/gradle/wrapper/gradle-wrapper.properties

@@ -3,4 +3,4 @@ distributionBase=GRADLE_USER_HOME
 distributionPath=wrapper/dists
 zipStoreBase=GRADLE_USER_HOME
 zipStorePath=wrapper/dists
-distributionUrl=https\://services.gradle.org/distributions/gradle-5.6.2-all.zip
+distributionUrl=https\://services.gradle.org/distributions/gradle-6.7.1-all.zip