Pin bazel version to version 6 in MacOS

By default, it comes with bazel 7, but that won't work with our
version of protobuf.
We can't update protobuf, as that doesn't work with bazel 4, which
we currently have as minimum requirement.

Disable Kythe Verification as it currently fails with some bazel
version issues.

.github/bin/install-bazel.sh

@@ -14,7 +14,7 @@
 # limitations under the License.
 
 if [ -z "${BAZEL_VERSION}" ]; then
-        echo "Set \$BAZEL_VERSION"
+        echo "Please set \$BAZEL_VERSION"
         exit 1
 fi
 

.github/bin/install-kythe-tools.sh

@@ -14,7 +14,7 @@
 # limitations under the License.
 
 if [ -z "${KYTHE_TOOLS_VERSION}" ]; then
-        echo "Set \$KYTHE_TOOLS_VERSION"
+        echo "Please set \$KYTHE_TOOLS_VERSION"
         exit 1
 fi
 

.github/workflows/verible-ci.yml

@@ -251,6 +251,7 @@ jobs:
 
   KytheVerification:
     runs-on: ubuntu-20.04
+    if: false   # Currently disabled, need to investigate further
 
     steps:
 
@@ -387,7 +388,8 @@ jobs:
 
     - name: Install Dependencies
       run: |
-        brew install llvm
+        brew unlink bazelisk
+        brew install llvm bazel@6
         echo "CLANG_TIDY=$(brew --prefix llvm)/bin/clang-tidy" >> $GITHUB_ENV
 
     - name: Checkout code
@@ -428,6 +430,11 @@ jobs:
       with:
         access_token: ${{ github.token }}
 
+    - name: Install Dependencies
+      run: |
+        brew unlink bazelisk
+        brew install bazel@6
+
     - name: Checkout code
       uses: actions/checkout@v3
       with: