ci: pin rust toolchain on 1.51.0 on windows-i686 target

.github/workflows/windows-i686.yml

@@ -20,7 +20,7 @@ jobs:
       - name: Setup node
         run: choco install nodejs-lts --x86 -y --force
 
-      - name: Set 32bit NodeJS path
+      - name: Set 32bit Node.js path
         run: |
           echo "C:\\Program Files (x86)\\nodejs" >> $GITHUB_PATH
         shell: bash
@@ -40,7 +40,7 @@ jobs:
       - name: Install
         uses: actions-rs/toolchain@v1
         with:
-          toolchain: stable
+          toolchain: 1.51.0
           profile: minimal
           override: true