Fix release hash validation on older Python

VIBE/CHAT_LOG.md

@@ -1490,3 +1490,9 @@ Make sure that when the plugin is signed the version in the link it the about pa
 
 ### Assistant outcome
 Extended `make update-updates` to set the About page plugin download URL to the newest valid signed XPI. Release validation now also rejects an About page whose link does not match the latest signed artifact; verified with LinkLog 0.2.0.
+
+### User
+Release script fails because the runner's hashlib module has no file_digest attribute.
+
+### Assistant outcome
+Replaced Python 3.11-only `hashlib.file_digest` calls in signed-XPI metadata generation and release validation with streaming SHA-256 calculations compatible with older Python runners. Regenerated update metadata and verified release validation passes.

VIBE/PROMPTS.md

@@ -267,6 +267,7 @@
 245. Add sha hashes to the updates.json
 246. Update changelog and VIBE
 247. Make sure that when the plugin is signed the version in the link it the about page is updated too
+248. Release script fails because the runner's hashlib module has no file_digest attribute.
 
 ## Future entries
 

scripts/release/generate_updates.py

@@ -38,8 +38,11 @@ def read_packaged_manifest(xpi_path: Path) -> dict:
 
 
 def sha256_digest(xpi_path: Path) -> str:
+    digest = hashlib.sha256()
     with xpi_path.open('rb') as xpi_file:
-        return hashlib.file_digest(xpi_file, 'sha256').hexdigest()
+        for block in iter(lambda: xpi_file.read(1024 * 1024), b''):
+            digest.update(block)
+    return digest.hexdigest()
 
 
 def update_about_plugin_link(xpi_path: Path) -> None:

scripts/release/validate_release.py

@@ -38,6 +38,14 @@ def find_latest_signed_xpi() -> tuple[str, Path]:
     return max(candidates, key=lambda candidate: version_key(candidate[0]))
 
 
+def sha256_digest(xpi_path: Path) -> str:
+    digest = hashlib.sha256()
+    with xpi_path.open('rb') as xpi_file:
+        for block in iter(lambda: xpi_file.read(1024 * 1024), b''):
+            digest.update(block)
+    return digest.hexdigest()
+
+
 def validate_self_update(source_manifest: dict, extension_version: str, xpi_path: Path) -> None:
     gecko_settings = source_manifest.get('browser_specific_settings', {}).get('gecko', {})
     addon_id = gecko_settings.get('id')
@@ -64,8 +72,7 @@ def validate_self_update(source_manifest: dict, extension_version: str, xpi_path
             f'the expected raw signed XPI URL {expected_link!r}'
         )
 
-    with xpi_path.open('rb') as xpi_file:
-        expected_hash = f'sha256:{hashlib.file_digest(xpi_file, "sha256").hexdigest()}'
+    expected_hash = f'sha256:{sha256_digest(xpi_path)}'
     if entry.get('update_hash') != expected_hash:
         fail(
             f'{UPDATES_PATH.relative_to(ROOT)} update_hash {entry.get("update_hash")!r} does not match '