[MacOS] Cache Python packages to reduce the bandwidth usage of PyPI.

.github/workflows/cpp-python-build.yml

@@ -447,6 +447,15 @@ jobs:
     steps:
       - name: Checkout JSBSim
         uses: actions/checkout@v4
+      - name: Cache Python packages & CTest cost data
+        # CTestCostData.txt is used by CTest to optimize the distribution of the
+        # tests between the CPU cores and reduce execution time.
+        uses: actions/cache@v4
+        with:
+          path: |
+            ~/Library/Caches/pip
+            build/Testing/Temporary/CTestCostData.txt
+          key: ${{ runner.os }}-${{ hashFiles('tests\CMakeLists.txt', 'python\requirements.tx') }}
       - name: Set up Python
         uses: actions/setup-python@v5
         with:
@@ -455,13 +464,6 @@ jobs:
         run: pip install -r python/requirements.txt
       - name: Set up Julia
         uses: julia-actions/setup-julia@v2
-      - name: Cache CTest cost data
-        # This file is used by CTest to optimize the distribution of the tests
-        # between the cores and reduce execution time.
-        uses: actions/cache@v4
-        with:
-          path: build/Testing/Temporary/CTestCostData.txt
-          key: ${{ matrix.os }}-${{ hashFiles('tests/CMakeLists.txt') }}
       - name: Install & Configure Doxygen
         if: env.release == 'true' && matrix.os == 'macos-13'
         run: |