Restore support for 3.7 and change flake8 and pytest installs

.github/workflows/python-package-conda.yml

@@ -17,7 +17,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        python-version: ["3.8", "3.9", "3.10", "3.11", "3.12"]
+        python-version: ["3.7", "3.8", "3.9", "3.10", "3.11", "3.12"]
       max-parallel: 5
 
     steps:
@@ -32,14 +32,14 @@ jobs:
         init-shell: bash
         create-args: >-
           python=${{ matrix.python-version }}
-          flake8
-          pytest
     - name: Lint with flake8
       run: |
+        mamba 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 --ignore=E501,W503,F841,E203
     - name: Test with pytest
       run: |
+        mamba install pytest
         pytest || true