CI: flake8: max-complexity=14 (#2731)

The value of 10 does not really fit some of our world patterns and values
up to 15 may be acceptable. Looking at some worlds, 14 seems to be
achievable without too much work and reduces the noise in test output,
making it more usable.

.github/workflows/analyze-modified-files.yml

@@ -71,7 +71,7 @@ jobs:
         continue-on-error: true
         if: env.diff != '' && matrix.task == 'flake8'
         run: |
-          flake8 --count --max-complexity=10 --max-doc-length=120 --max-line-length=120 --statistics ${{ env.diff }}
+          flake8 --count --max-complexity=14 --max-doc-length=120 --max-line-length=120 --statistics ${{ env.diff }}
 
       - name: "mypy: Type check modified files"
         continue-on-error: true