GHA: use pip requirements.txt with pins, and more venv

- requirements.txt: shorten copyright headers.

- requirements.txt: pin packages to versions.

- GHA/windows: use `tests/requirements.txt`.
  Pick a `cryptography` package version that satifies both `impacket`
  and pytests dependencies.

- GHA/checksrc: move pip deps into a new `requirements.txt`.
  To make Dependabot detect and bump them.

- GHA/checksrc: replace apt packages for python test deps with pip
  install `tests/**/requirements.txt` to a venv.

- GHA/checksrc: use venv and drop `--break-system-packages`.

- GHA/linux: fix to actually activate venvs.
  Follow-up to 2638570241 #15578

- GHA/linux: fixup (did not cause an issue)
  Follow-up to d75785c7de #18660

- GHA: create venvs later, simplify commands.

- GHA: sync pip command-line options, e.g. drop progress-bar,
  everywhere.

Assisted-by: Dan Fandrich

Closes #18708

.github/workflows/checksrc.yml

@@ -55,18 +55,15 @@ jobs:
         env:
           DEBIAN_FRONTEND: noninteractive
         run: |
-          sudo rm -f /etc/apt/sources.list.d/microsoft-prod.list
-          sudo apt-get -o Dpkg::Use-Pty=0 update
-          sudo rm -f /var/lib/man-db/auto-update
-          sudo apt-get -o Dpkg::Use-Pty=0 install \
-            python3-pip python3-networkx python3-pydot python3-yaml \
-            python3-toml python3-markupsafe python3-jinja2 python3-tabulate \
-            python3-typing-extensions python3-libcst python3-impacket \
-            python3-websockets python3-pytest python3-filelock python3-pytest-xdist
-          python3 -m pip install --break-system-packages cmakelang==0.6.13 pytype==2024.10.11 ruff==0.11.9 codespell==2.4.1
+          python3 -m venv ~/venv
+          ~/venv/bin/pip --disable-pip-version-check --no-input --no-cache-dir install --progress-bar off --prefer-binary \
+            -r .github/scripts/requirements.txt \
+            -r tests/http/requirements.txt \
+            -r tests/requirements.txt
 
       - name: 'codespell'
         run: |
+          source ~/venv/bin/activate
           codespell --version
           .github/scripts/codespell.sh
 
@@ -78,13 +75,19 @@ jobs:
           .github/scripts/typos.sh
 
       - name: 'cmakelint'
-        run: scripts/cmakelint.sh
+        run: |
+          source ~/venv/bin/activate
+          scripts/cmakelint.sh
 
       - name: 'pytype'
-        run: find . -name '*.py' -exec pytype -j auto -k {} +
+        run: |
+          source ~/venv/bin/activate
+          find . -name '*.py' -exec pytype -j auto -k {} +
 
       - name: 'ruff'
-        run: scripts/pythonlint.sh
+        run: |
+          source ~/venv/bin/activate
+          scripts/pythonlint.sh
 
   reuse:
     name: 'REUSE'