[ci] Minor fixes

- Enable CI only for PR.
- Add missing keys for Android Beta.

Signed-off-by: Roman Tsisyk <roman@tsisyk.com>

.github/workflows/android-beta.yaml

@@ -7,7 +7,7 @@ on:
 jobs:
   android-beta:
     name: Android Beta
-    runs-on: [self-hosted, linux, X64]
+    runs-on: ubuntu-latest
     steps:
       - name: Set up JDK 1.8
         uses: actions/setup-java@v1
@@ -19,6 +19,14 @@ jobs:
         with:
           submodules: recursive
 
+      - name: Checkout keys
+        uses: actions/checkout@v2
+        with:
+          repository: omapsapp/omapsapp-release-keys
+          path: private/release
+          ref: release
+          ssh-key: ${{ secrets.SSH_PRIVATE_KEY }}
+
       - name: Remove old outputs
         shell: bash
         run: |
@@ -32,7 +40,7 @@ jobs:
       - name: Set up SDK
         shell: bash
         run: |
-          (cd tools/android; ./set_up_android.py --sdk $ANDROID_SDK_ROOT= --ndk $ANDROID_NDK_ROOT)
+          (cd tools/android; ./set_up_android.py --sdk $ANDROID_SDK_ROOT --ndk $ANDROID_NDK_ROOT)
 
       - name: Compile
         shell: bash

.github/workflows/android-check.yaml

@@ -1,6 +1,5 @@
 name: Check
 on:
-  push:
   pull_request:
 
 jobs:
@@ -28,12 +27,6 @@ jobs:
         run: |
           (cd tools/android; ./set_up_android.py --sdk $ANDROID_SDK_ROOT --ndk $ANDROID_NDK_ROOT)
 
-      - name: Restore cache
-        uses: actions/cache@v2
-        with:
-          path: android/nativeOutputs
-          key: android-cache
-
       - name: Compile
         shell: bash
         run: (cd android; ./gradlew -Parm64 assembleWebDebug)

.github/workflows/desktop-check.yaml

@@ -1,6 +1,5 @@
 name: Check
 on:
-  push:
   pull_request:
 
 jobs:

.github/workflows/ios-check.yaml

@@ -1,6 +1,5 @@
 name: Check
 on:
-  push:
   pull_request:
 
 jobs: