Update GitHub Actions workflow versions (#668)

Changes:
- checkout is now at v4
- AWS credential configuration v3+ has a fix for the deprecated
  JavaScript SDK, v4 updates the Node version
- There's now a Julia-specific caching action
- Ditto for documentation

.github/workflows/CI.yml

@@ -34,9 +34,9 @@ jobs:
             version: "1.6"
             arch: x64
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v4
       - name: Assume AWS role
-        uses: aws-actions/configure-aws-credentials@v2
+        uses: aws-actions/configure-aws-credentials@v4
         with:
           role-to-assume: arn:aws:iam::${{ secrets.AWS_ACCOUNT_ID }}:role/AWS.jl
           aws-region: us-east-1
@@ -69,16 +69,7 @@ jobs:
         with:
           version: ${{ matrix.version }}
           arch: ${{ matrix.arch }}
-      - uses: actions/cache@v1
-        env:
-          cache-name: cache-artifacts
-        with:
-          path: ~/.julia/artifacts
-          key: ${{ runner.os }}-test-${{ env.cache-name }}-${{ hashFiles('**/Project.toml') }}
-          restore-keys: |
-            ${{ runner.os }}-test-${{ env.cache-name }}-
-            ${{ runner.os }}-test-
-            ${{ runner.os }}-
+      - uses: julia-actions/cache@v1
       - uses: julia-actions/julia-buildpkg@latest
       - run: |
           git config --global user.name Tester
@@ -88,16 +79,12 @@ jobs:
     name: Documentation
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v4
       - uses: julia-actions/setup-julia@v1
         with:
           version: '1'
-      - run: |
-          julia --project=docs -e '
-            using Pkg
-            Pkg.develop(PackageSpec(path=pwd()))
-            Pkg.instantiate()
-            include("docs/make.jl")'
+      - uses: julia-actions/julia-buildpkg@latest
+      - uses: julia-actions/julia-docdeploy@latest
         env:
           GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
           DOCUMENTER_KEY: ${{ secrets.DOCUMENTER_KEY }}