GH: fixing paths, hopefully cache starts working on unix

.github/workflows/pytest.yml

@@ -36,8 +36,8 @@ jobs:
         uses: actions/cache@v3
         with:
           path: |
-            ~/go/bin
-            ~/.cache/go-build
+            ${{ env.HOME }}/go/bin
+            ${{ env.HOME }}/.cache/go-build
           key: go-binaries-${{ runner.os }}-gopls-latest
       - name: Install gopls
         if: steps.cache-go-binaries.outputs.cache-hit != 'true'
@@ -77,7 +77,7 @@ jobs:
         id: cache-language-servers
         uses: actions/cache@v3
         with:
-          path: ~/.serena/language_servers/static
+          path: ${{ env.HOME }}/.serena/language_servers/static
           key: language-servers-${{ runner.os }}-v1
           restore-keys: |
             language-servers-${{ runner.os }}-