fix: record each platform's own list version

install/<platform>.json wrote the constant "1.0" as the version of the
list it was built from. The manifest now carries the version the platform
YAML records, and generate_pack refuses a YAML without one.

inherits: no longer passes a parent's version to a child: Lakka was
published as RetroArch v1.22.2 in its manifest, pack name and site page.
lakka.yml records v6.1, the Lakka-LibreELEC tag its target list is read
at. The MiSTer scraper refuses a BiosDB without a timestamp instead of
writing an empty version.

A pack's manifest.json records list_version, so an install from the pack
alone knows it too. Manifests regenerated twice and compared: only
version and generated changed.

tests/test_no_game_data.py

@@ -92,7 +92,7 @@ class _Fixture(unittest.TestCase):
         for key, profile in PROFILES.items():
             (self.emulators / f"{key}.yml").write_text(yaml.dump(profile))
         platform = {
-            "platform": "Handheld", "verification_mode": "existence",
+            "platform": "Handheld", "version": "2.1", "verification_mode": "existence",
             "cores": ["emu", "doomcore"],
             "systems": {
                 "console": {"files": [{"name": "firmware.rom", "destination": "firmware.rom"}]},