chore: BCR testing on Bazel 6 and 7 (#125)

Merge bazel-contrib/rules-template#105

Author: alexeagle

.bcr/presubmit.yml

@@ -1,10 +1,12 @@
 bcr_test_module:
   module_path: "example"
   matrix:
+    bazel: ["7.x", "6.x"]
     platform: ["debian10", "macos", "ubuntu2004"]
   tasks:
     run_tests:
       name: "Run test module"
+      bazel: ${{ bazel }}
       platform: ${{ platform }}
       environment:
         BAZELISK_BASE_URL: "https://github.com/bazelbuild/bazel/releases/download/"