Set default Bazel versions to be tested (#105)

Author: meteorcloudy

.bcr/presubmit.yml

@@ -2,9 +2,11 @@ bcr_test_module:
   module_path: "e2e/smoke"
   matrix:
     platform: ["debian10", "macos", "ubuntu2004", "windows"]
+    bazel: ["7.x", "6.x"]
   tasks:
     run_tests:
       name: "Run test module"
       platform: ${{ platform }}
+      bazel: ${{ bazel }}
       test_targets:
         - "//..."