fix(plugins): restore the hello fixture's source fingerprint

The recorded fingerprint did not match the fixture's sources, so
plugins/build.sh --check reported the fixture as stale.

crates/ide-plugin/tests/fixtures/hello/dist/plugin.wasm.sources

@@ -1 +1 @@
-d1bdd0c36fd409b5e4b22e7206ff3ff9afa30f957055d89f25f573f241131892
+a50d1eb41ab8dd0c9c8d6bae8266906cd6eb5de8e6f6ca6f681990389472bb5b