Cache requests when doing the linkcheck ci test.

At some point, we must have split out the linkcheck test from the docs test, but forgot to update the cache settings.

.github/workflows/linuxtests.yml

@@ -42,7 +42,7 @@ jobs:
           node-version: '12.x'
 
       - name: Cache pip on Linux
-        uses: actions/cache@v1
+        uses: actions/cache@v2
         if: startsWith(runner.os, 'Linux')
         with:
           path: ~/.cache/pip
@@ -54,7 +54,7 @@ jobs:
         id: yarn-cache-dir-path
         run: echo "::set-output name=dir::$(yarn cache dir)"
       - name: Cache yarn
-        uses: actions/cache@v1
+        uses: actions/cache@v2
         id: yarn-cache # use this to check for `cache-hit` (`steps.yarn-cache.outputs.cache-hit != 'true'`)
         with:
           path: ${{ steps.yarn-cache-dir-path.outputs.dir }}
@@ -63,13 +63,13 @@ jobs:
             ${{ runner.os }}-yarn-
 
       - name: Cache checked links build
-        uses: actions/cache@v1
-        if: ${{ matrix.group == 'docs' }}
+        uses: actions/cache@v2
+        if: ${{ matrix.group == 'linkcheck' }}
         with:
           path: ~/.cache/pytest-link-check
-          key: ${{ runner.os }}-link-check-${{ hashFiles('**/*.rst') }}
+          key: ${{ runner.os }}-linkcheck-${{ hashFiles('**/*.rst') }}
           restore-keys: |
-            ${{ runner.os }}-link-check-
+            ${{ runner.os }}-linkcheck-
 
       - name: Install dependencies
         env: