Update .bazelci/presubmit.yml

Co-authored-by: Brentley Jones <[email protected]>

Author: keith

.bazelci/presubmit.yml

@@ -25,7 +25,7 @@ tasks:
 
   macos_7_workspace:
     name: "7.x WORKSPACE"
-    bazel: latest
+    bazel: 7.x
     <<: *common
     build_flags:
     - --enable_bzlmod=false