fix: set release-please manifest to last stable tag (v0.11.2)

The manifest was set to 0.12.0, but that version was never released
as a stable tag — only beta tags exist. This caused release-please
to diff against a nonexistent tag and pull in the entire project
history. Reset to 0.11.2 so the next release correctly diffs from
the last stable release.

Author: nicknisi

.release-please-manifest.json

@@ -1,3 +1,3 @@
 {
-  ".": "0.12.0"
+  ".": "0.11.2"
 }