[CI] Add Android CI (#163)

### Motivation

OpenAPI Runtime works on Android, we just don't CI it so it might
regress.

The SPI badge confirms the Android support here.

### Modifications

Added CI for Android.

### Result

More confidence when making changes that we're not breaking Android
users.

### Test Plan

PR CI.

Author: czechboy0

.github/workflows/main.yml

@@ -62,6 +62,11 @@ jobs:
     # Workaround https://github.com/nektos/act/issues/1875
     uses: apple/swift-nio/.github/workflows/static_sdk.yml@main
 
+  android-sdk:
+    name: Android Swift SDK
+    # Workaround https://github.com/nektos/act/issues/1875
+    uses: apple/swift-nio/.github/workflows/android_swift_sdk.yml@main
+
   macos-tests:
     name: macOS tests
     uses: apple/swift-nio/.github/workflows/macos_tests.yml@main

.github/workflows/pull_request.yml

@@ -66,6 +66,11 @@ jobs:
     # Workaround https://github.com/nektos/act/issues/1875
     uses: apple/swift-nio/.github/workflows/static_sdk.yml@main
 
+  android-sdk:
+    name: Android Swift SDK
+    # Workaround https://github.com/nektos/act/issues/1875
+    uses: apple/swift-nio/.github/workflows/android_swift_sdk.yml@main
+
   macos-tests:
     name: macOS tests
     uses: apple/swift-nio/.github/workflows/macos_tests.yml@main