Try to fix CI warning

.github/workflows/testsuite.yml

@@ -47,17 +47,25 @@ jobs:
       with:
         python-version: ${{ matrix.python-version }}
 
-    - name: Get pip cache dir
-      id: pip-cache
+    - name: Get pip cache dir Unix
+      if: matrix.os != 'windows-latest'
+      id: pip-cache-unix
       run: |
         python -m pip install --upgrade pip
-        echo "::set-output name=dir::$(pip cache dir)"
+        echo "dir=$(pip cache dir)" >> $GITHUB_OUTPUT
+
+    - name: Get pip cache dir Windows
+      if: matrix.os == 'windows-latest'
+      id: pip-cache-windows
+      run: |
+        python -m pip install --upgrade pip
+        echo "dir=$(pip cache dir)" >> $env:GITHUB_OUTPUT
 
     - name: Cache dependencies
       id: cache-dep
       uses: actions/cache@v4
       with:
-        path: ${{ steps.pip-cache.outputs.dir }}
+        path: if [[ '${{ matrix.os }}' == 'windows-latest' ]]; then ${{ steps.pip-cache-windows.outputs.dir }}; else ${{ steps.pip-cache-unix.outputs.dir }}; fi
         key: ${{ matrix.os }}-${{ matrix.python-version }}-pip-${{ hashFiles('**/requirements.txt') }}-${{ hashFiles('**/extra_requirements.txt') }}-${{ hashFiles('**/legacy_requirements.txt') }}
         restore-keys: |
           ${{ matrix.os }}-${{ matrix.python-version }}-pip-