Revert "Use the cache action"

This reverts commit bf1e97d.

Author: seisman

.github/workflows/ci_tests.yaml

@@ -69,16 +69,6 @@ jobs:
           # fecth all history so that setuptools-scm works
           fetch-depth: 0
 
-      - name: Cache conda
-        uses: actions/cache@v1
-        env:
-          # Increase this value to reset cache if etc/example-environment.yml has not changed
-          CACHE_NUMBER: 0
-        with:
-          path: ~/conda_pkgs_dir
-          key:
-            ${{ runner.os }}-conda-${{ env.CACHE_NUMBER }}-${{ hashFiles('environment.yml') }}
-
       # Install Mambaforge with conda-forge dependencies
       - name: Setup Mambaforge
         uses: conda-incubator/setup-miniconda@2fc91a2ef82dfb50ded2d80e56f83b7039ba5955