Make GitHub Actions use Pipenv for installing deps

For:
#28

.github/workflows/check.yml

@@ -11,13 +11,15 @@ jobs:
         uses: actions/setup-python@v5
         with:
           python-version: "3.12"
+      - name: install Pipenv
+        run: pip install pipenv --user
       - name: install dependencies
-        run: pip install -r requirements.txt
+        run: pipenv sync --dev # Installs all deps, including dev deps, from Pipfile.lock.
       - name: Format
-        run: invoke fmt
+        run: pipenv run invoke fmt
       - name: lint
-        run: invoke lint
+        run: pipenv run invoke lint
       - name: check types
-        run: invoke types
+        run: pipenv run invoke types
       - name: run tests
-        run: invoke test
+        run: pipenv run invoke test

tasks.py

@@ -58,26 +58,6 @@ def check(c):
     """Run all code checks."""
 
 
-@task
-def reqs(c):
-    """Generate requirements.txt file.
-
-    The GitHub Actions workflow runners don't seem to play nicely with
-    Pipenv. We generate a requirements.txt file and use it to install
-    dependencies in GitHub Actions.
-
-    We also use the requirements.txt file on Elastic Beanstalk.
-    """
-    add_warning = (
-        "echo '# Do not edit directly. This file is generated.\n' > requirements.txt"
-    )
-    # The PIPENV_VERBOSITY variable suppresses a warning issued Pipenv
-    # if you use the run command when you've already activated the
-    # virtual environment.
-    add_reqs = "PIPENV_VERBOSITY=-1 pipenv run pip freeze >> requirements.txt"
-    c.run(f"{add_warning} && {add_reqs}")
-
-
 @task
 def dev(c):
     """Run the development server.