use pinned requirements files in CI

.github/workflows/docs.yaml

@@ -25,8 +25,8 @@ jobs:
       - name: Install dependencies
         run: |
           pip install --upgrade pip
-          pip install -r requirements/minimal.txt
-          pip install -r requirements/docs.txt
+          pip install -r requirements_minimal_CI.txt
+          pip install -r requirements_docs_CI.txt
           python -m pip install build packaging
 
       - name: Build package

.github/workflows/lint.yaml

@@ -17,10 +17,10 @@ jobs:
 
       - name: Install dependencies
         run: |
-          pip install -r requirements/minimal.txt
-          pip install -r requirements/lint.txt
+          pip install -r requirements_minimal_CI.txt
+          pip install -r requirements_lint_CI.txt
           # Mypy also checks types in the tests/ folder
-          pip install -r requirements/tests.txt
+          pip install -r requirements_tests_CI.txt
           python setup.py build
 
       - name: black

.github/workflows/tests.yaml

@@ -43,8 +43,8 @@ jobs:
 
       - name: install dependencies
         run: |
-          pip install -r requirements/minimal.txt
-          pip install -r requirements/tests.txt
+          pip install -r requirements_minimal_CI.txt
+          pip install -r requirements_tests_CI.txt
 
       # Check that demes installs as expected.
       # Also check the "demes" CLI entry point.

.github/workflows/wheel.yaml

@@ -18,7 +18,7 @@ jobs:
 
       - name: install dependencies
         run: |
-          pip install -r requirements/minimal.txt
+          pip install -r requirements_minimal_CI.txt
           pip install build
 
       - name: build wheel