[github] Use cache for android externals

This commit updates android build workflow to use cache for externals directory.

ONE-DCO-1.0-Signed-off-by: Hyeongseok Oh <[email protected]>

.github/workflows/run-onert-android-build.yml

@@ -41,6 +41,22 @@ jobs:
       - name: Checkout
         uses: actions/checkout@v4
 
+      - name: Get hash
+        run: |
+          echo "PKG_HASH=$(git log --pretty=tformat:'%h' -n1 infra/cmake)" >> $GITHUB_ENV
+          echo "RUN_PKG_HASH=$(git log --pretty=tformat:'%h' -n1 infra/nnfw/cmake)" >> $GITHUB_ENV
+
+      - name: Caching externals
+        uses: actions/cache@v4
+        with:
+          path: ~/externals
+          key: external-onert-ndk26-${{ env.PKG_HASH }}-${{ env.RUN_PKG_HASH }}
+          restore-keys: |
+            external-onert-ndk26-${{ env.PKG_HASH }}
+            external-onert-ndk26-
+            external-onert-
+            external-
+
       # numpy: test build
       # scons: arm compute library build
       - name: Install packages