scripts/ tests/: don't run pip install within individual tests.

Instead have added missing flake8 to scripts/gh_release.py:test_packages, so
all required packages will already be available, e.g. when tests are run by
`scripts/test.py`.

This addresses pymupdf#2950 "Shelling out to pip during tests is problematic".

scripts/gh_release.py

@@ -661,7 +661,7 @@ def platform_tag():
 # If this has changed, need to update
 # .github/workflows/*.yml.
 #
-test_packages = 'pytest fontTools psutil pymupdf-fonts'
+test_packages = 'pytest fontTools psutil pymupdf-fonts flake8'
 if platform.system() == 'Windows' and cpu_bits() == 32:
     # No pillow wheel available, and doesn't build easily.
     pass

tests/test_flake8.py

@@ -12,10 +12,6 @@ def test_flake8():
     if not hasattr(fitz, 'mupdf'):
         print(f'Not running flake8 with classic implementation.')
         return
-    if sys.prefix == sys.base_prefix:
-        # We install flake8, which we only want to do if we are in a venv.
-        print(f'Not running flake8 because we are not in a venv.')
-        return
     ignores = (
             'E123', # closing bracket does not match indentation of opening bracket's line
             'E124', # closing bracket does not match visual indentation
@@ -53,6 +49,5 @@ def test_flake8():
     def run(command):
         print(f'test_flake8(): Running: {command}')
         subprocess.run(command, shell=1, check=1)
-    run(f'pip install flake8')
     run(f'flake8 --ignore={ignores} --statistics {root}/src/__init__.py {root}/src/utils.py {root}/src/table.py')
     print(f'test_flake8(): flake8 succeeded.')

tests/test_font.py

@@ -60,7 +60,6 @@ def test_2608():
 
 def test_fontarchive():
     import subprocess
-    subprocess.run('pip install pymupdf-fonts', shell=1, check=1)
     arch = fitz.Archive()
     css = fitz.css_for_pymupdf_font("notos", archive=arch, name="sans-serif")
     print(css)