Upgrade CI deps

Author: chenglou

syntax/.github/workflows/ci.yml

@@ -11,27 +11,27 @@ jobs:
     runs-on: macos-latest
 
     steps:
-    - uses: actions/checkout@v2
+    - uses: actions/checkout@v2.3.4
 
     - name: Cache OCaml's opam
-      uses: actions/[email protected].0
+      uses: actions/[email protected].5
       with:
         path: ~/.opam
         key: macos-latest-ocaml-4.06.1
 
     - name: Cache npm
-      uses: actions/[email protected].0
+      uses: actions/[email protected].5
       with:
         path: ~/.npm
         key: macos-latest-node-14.4.0-${{hashFiles('package-lock.json')}}
 
     - name: Use OCaml
-      uses: avsm/setup-ocaml@v1
+      uses: avsm/setup-ocaml@v1.1.10
       with:
         ocaml-version: 4.06.1
 
     - name: Use Node.js
-      uses: actions/setup-node@v1
+      uses: actions/setup-node@v2.1.5
       with:
         node-version: 14.4.0