build: Upgrade workflows to Bazel 8

- Ask for WORKSPACE support explicitly (now disabled by default).
- Remove 'compatibility_level' from module() (now deprecated/no-op).

Author: jdcormie

.github/workflows/testing.yml

@@ -81,7 +81,7 @@ jobs:
       matrix:
         bzlmod: [true, false]
     env:
-      USE_BAZEL_VERSION: 7.7.1
+      USE_BAZEL_VERSION: 8.7.0
 
     steps:
     - uses: actions/checkout@v4
@@ -100,11 +100,11 @@ jobs:
         key: ${{ runner.os }}-bazel-${{ env.USE_BAZEL_VERSION }}-${{ hashFiles('WORKSPACE', 'repositories.bzl') }}
 
     - name: Run bazel build
-      run: bazelisk build //... --enable_bzlmod=${{ matrix.bzlmod }}
+      run: bazelisk build //... --enable_bzlmod=${{ matrix.bzlmod }} --enable_workspace=${{ !matrix.bzlmod }}
 
     - name: Run bazel test
-      run: bazelisk test //... --enable_bzlmod=${{ matrix.bzlmod }}
+      run: bazelisk test //... --enable_bzlmod=${{ matrix.bzlmod }} --enable_workspace=${{ !matrix.bzlmod }}
 
     - name: Run example bazel build
-      run: bazelisk build //... --enable_bzlmod=${{ matrix.bzlmod }}
+      run: bazelisk build //... --enable_bzlmod=${{ matrix.bzlmod }} --enable_workspace=${{ !matrix.bzlmod }}
       working-directory: ./examples

MODULE.bazel

@@ -1,7 +1,6 @@
 module(
     name = "grpc-java",
     version = "1.82.0-SNAPSHOT",  # CURRENT_GRPC_VERSION
-    compatibility_level = 0,
     repo_name = "io_grpc_grpc_java",
 )