share lockfile between lint and docs

Author: gilesknap

.dockerignore

@@ -1,3 +1,5 @@
+# Ignore folders that can be large.
+# This saves time copying them into the context at the start of a build.
 build/
 .mypy_cache
 .tox

.github/workflows/code.yml

@@ -23,7 +23,7 @@ jobs:
       - name: Install python packages
         uses: ./.github/actions/install_requirements
         with:
-          requirements_file: requirements-lint.txt
+          requirements_file: requirements-dev-3.x.txt
           install_options: -e .[dev]
 
       - name: Lint

.github/workflows/docs.yml

@@ -27,7 +27,7 @@ jobs:
       - name: Install python packages
         uses: ./.github/actions/install_requirements
         with:
-          requirements_file: requirements-docs.txt
+          requirements_file: requirements-dev-3.x.txt
           install_options: -e .[dev]
 
       - name: Build docs