chore(deps-dev): bump pnpm from 8.7.5 to 9.15.0

Bumps [pnpm](https://github.com/pnpm/pnpm/tree/HEAD/pnpm) from 8.7.5 to 9.15.0.
- [Release notes](https://github.com/pnpm/pnpm/releases)
- [Changelog](https://github.com/pnpm/pnpm/blob/v9.15.0/pnpm/CHANGELOG.md)
- [Commits](https://github.com/pnpm/pnpm/commits/v9.15.0/pnpm)

---
updated-dependencies:
- dependency-name: pnpm
  dependency-type: direct:development
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

package.json

@@ -2,7 +2,7 @@
   "name": "@erc6900/reference-implementation",
   "version": "0.8.0",
   "devDependencies": {
-    "pnpm": "^8.7.5",
+    "pnpm": "^9.15.0",
     "solhint": "^3.6.2"
   },
   "scripts": {