Add bazel matrix to presubmit.yml (#115)

.bcr/presubmit.yml

@@ -1,27 +1,32 @@
 matrix:
+  bazel: [6.x, 7.x]
   platform: ["centos7", "debian10", "macos", "ubuntu2004", "windows"]
 
 tasks:
   build_targets:
     name: "Build targets under //jni"
+    bazel: ${{ bazel }}
     platform: ${{ platform }}
     build_targets:
       - "@rules_jni//jni/..."
 
 bcr_test_module:
   module_path: "tests"
   matrix:
+    bazel: [6.x, 7.x]
     platform: ["debian10", "macos", "ubuntu2004", "windows"]
   tasks:
     run_tests:
       name: "Run test module"
+      bazel: ${{ bazel }}
       platform: ${{ platform }}
       test_targets:
         - "//..."
     # The CentOS image does not set JAVA_HOME. To make the tests work, we set it
     # manually.
     run_tests_centos7:
       name: "Run test module"
+      bazel: ${{ bazel }}
       platform: centos7
       environment:
         JAVA_HOME: /usr/lib/jvm/java-1.8.0