updating actions/cache github action, old version deprecated

Author: ZelenyMartin

.github/workflows/main.yml

@@ -13,12 +13,12 @@ jobs:
       with:
         python-version: 3.9
     - name: Poetry cache
-      uses: actions/cache@v2
+      uses: actions/cache@v4
       with:
         path: ~/.cache/pypoetry
         key: poetry-cache-${{ runner.os }}-${{ hashFiles('poetry.lock') }}-${{ hashFiles('.github/workflows/*.yml') }}
     - name: Pip cache
-      uses: actions/cache@v2
+      uses: actions/cache@v4
       with:
         path: ~/.cache/pip
         key: pip-cache-${{ runner.os }}-${{ hashFiles('.github/workflows/*.yml') }}