add version check

.github/workflows/version-check.yml

@@ -0,0 +1,20 @@
+name: C# SDK Version Check
+on:
+  push:
+    tags:
+      - 'v[0-9]+.[0-9]+.[0-9]+'
+jobs:
+  linux:
+    name: Version Check
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v2
+      - name: Set env
+        run: echo "RELEASE_VERSION=${GITHUB_REF#refs/*/v}" >> $GITHUB_ENV
+      - name: Check
+        run: |
+          set -e
+          grep -qF "<Version>${RELEASE_VERSION}</Version>" src/Qiniu/Qiniu.csproj
+          grep -qF "v${RELEASE_VERSION}" CHANGELOG.md
+          grep -qF "public const string VERSION = \"${RELEASE_VERSION}\";" src/Qiniu/QiniuCSharpSDK.cs