fix(ci): pin Bun version to 1.3.9 to fix ESM spyOn flakiness

Author: Slyrian

.github/workflows/release-please.yml

@@ -40,7 +40,7 @@ jobs:
 
       - uses: oven-sh/setup-bun@v2
         with:
-          bun-version: latest
+          bun-version: "1.3.9"
 
       - name: Install dependencies
         run: bun install --frozen-lockfile