Update embedpdf-snippet to version 2.9.1

- Updated the embedpdf-snippet dependency in package.json from version 2.3.0 to 2.9.1.
- Updated the upstream version file to reflect the new version.
- Removed the old embedpdf-snippet-2.3.0.tgz file.
- Added the new embedpdf-snippet-2.9.1.tgz file.

vendor/embedpdf/.upstream-version

@@ -1 +1 @@
-2.3.0
+2.9.1