release: 0.1.7 - pin to firefox-7 (issue #18 real fix)

Bumps BINARY_VERSION to firefox-7 which ships the real fix for issue #18
(id.sky.com tab crash on Windows headless=True).

firefox-7 contents:
- Canvas2D getImageData stealth spoof moved from read-only mapped surface
  to JS Uint8ClampedArray writable buffer (commit 2e17b4871f93 in
  invisible-firefox). Fixes the segfault on GPU-backed canvases that hit
  during page unload.

Paired with the wrapper-side security.sandbox.content.level=4 workaround
shipped in 2e0adbd (this repo), the combination resolves both halves of
issue #18: cross-process navigation crash in loop AND segfault at close.

End-to-end tested with InvisiblePlaywright headless=True + UK proxy on
id.sky.com: page survives 30s+, no crash in loop, no crash at close.

firefox-6 was rolled back when its partial-fix hypothesis turned out to
be the wrong root cause. Skipping straight to firefox-7.

pyproject.toml

@@ -4,7 +4,7 @@ build-backend = "hatchling.build"
 
 [project]
 name = "invisible-playwright"
-version = "0.1.6"
+version = "0.1.7"
 description = "Playwright wrapper for a patched Firefox with deterministic stealth profile."
 readme = "README.md"
 requires-python = ">=3.11"