Update unittests to use latest github checkout

.github/workflows/package_and_test.yml

@@ -8,29 +8,12 @@ on:
     - cron: '0 0 1 * *'
 
 jobs:
-  lint-linux:
-    runs-on: ubuntu-latest
-    strategy:
-      max-parallel: 5
-    steps:
-    - uses: actions/checkout@v2
-    - name: Add conda to system path
-      run: |
-        # $CONDA is an environment variable pointing to the root of the miniconda directory
-        echo $CONDA/bin >> $GITHUB_PATH
-    - name: Lint with flake8
-      run: |
-        conda install flake8
-        # stop the build if there are Python syntax errors or undefined names
-        flake8 . --count --select=E9,F63,F7,F82 --show-source --statistics
-        # exit-zero treats all errors as warnings. The GitHub editor is 127 chars wide
-        flake8 . --count --exit-zero --max-complexity=10 --max-line-length=127 --statistics
   build-linux:
     runs-on: ubuntu-latest
     strategy:
       max-parallel: 5
     steps:
-    - uses: actions/checkout@v2
+    - uses: actions/checkout@v4
     - name: Add conda to system path
       run: |
         # $CONDA is an environment variable pointing to the root of the miniconda directory
@@ -50,7 +33,7 @@ jobs:
     strategy:
       max-parallel: 5
     steps:
-    - uses: actions/checkout@v2
+    - uses: actions/checkout@v4
     - name: Add conda to system path
       run: |
         # $CONDA is an environment variable pointing to the root of the miniconda directory