actions: update checkouts to v2

.github/workflows/build-docs.yml

@@ -14,7 +14,7 @@ jobs:
     name: docs
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v1
+      - uses: actions/checkout@v2
       - name: Install Dependencies
         run: sudo pip3 install sphinx-rtd-theme
       - name: Build documentation

.github/workflows/check-patches.yml

@@ -17,7 +17,7 @@ jobs:
     name: Check patches
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v1
+      - uses: actions/checkout@v2
       - name: Refresh patches
         run: make refresh-patches GLUON_SITEDIR="contrib/ci/minimal-site"
       - name: Show diff

.github/workflows/lint.yml

@@ -8,7 +8,7 @@ jobs:
     name: Lua
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v1
+      - uses: actions/checkout@v2
       - name: Install Dependencies
         run: sudo apt install lua-check
       - name: Install example site
@@ -20,7 +20,7 @@ jobs:
     name: Shell
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v1
+      - uses: actions/checkout@v2
       - name: Install Dependencies
         run: sudo apt install shellcheck
       - name: Install example site