ci: bump actions/cache to v4

Link: https://github.com/actions/cache
Signed-off-by: Ariel Otilibili <otilibil@eurecom.fr>

Author: ariel-anieli

.github/workflows/ci.yml

@@ -13,7 +13,7 @@ jobs:
       - uses: actions/setup-python@v4
         with:
           python-version: 3.x
-      - uses: actions/cache@v3
+      - uses: actions/cache@v4
         with:
           path: ~/.cache/pip
           key: pip
@@ -61,7 +61,7 @@ jobs:
       - uses: actions/setup-python@v4
         with:
           python-version: ${{ matrix.python }}
-      - uses: actions/cache@v3
+      - uses: actions/cache@v4
         with:
           path: ~/.cache/pip
           key: pip
@@ -77,7 +77,7 @@ jobs:
       - uses: actions/setup-python@v4
         with:
           python-version: 3.x
-      - uses: actions/cache@v3
+      - uses: actions/cache@v4
         with:
           path: ~/.cache/pip
           key: pip
@@ -96,7 +96,7 @@ jobs:
       - uses: actions/setup-python@v4
         with:
           python-version: 3.x
-      - uses: actions/cache@v3
+      - uses: actions/cache@v4
         with:
           path: ~/.cache/pip
           key: pip