Fix ci failed on macos env. (#288)

Author: shibd

.github/workflows/ci-pr-validation.yaml

@@ -49,8 +49,11 @@ jobs:
 
       - name: Install deps (macOS)
         if: ${{ startsWith(matrix.os, 'macos') }}
-        run:
-          brew install pkg-config wireshark protobuf
+        run: |
+          # Install protobuf v21.12
+          wget https://raw.githubusercontent.com/Homebrew/homebrew-core/2d47ed2eac09d59ffc2c92b1d804f1c232188c88/Formula/protobuf.rb
+          brew install --formula ./protobuf.rb
+          brew install pkg-config wireshark
 
       - name: Build wireshark plugin
         run: |
@@ -267,7 +270,11 @@ jobs:
         uses: actions/checkout@v3
 
       - name: Install dependencies
-        run: brew install openssl protobuf boost zstd snappy googletest
+        run: |
+         # Install protobuf v21.12
+         wget https://raw.githubusercontent.com/Homebrew/homebrew-core/2d47ed2eac09d59ffc2c92b1d804f1c232188c88/Formula/protobuf.rb
+         brew install --formula ./protobuf.rb
+         brew install openssl boost zstd snappy googletest
 
       - name: Configure (default)
         shell: bash