chore: Update CONTRIBUTING.md

Author: TkDodo

CONTRIBUTING.md

@@ -18,7 +18,7 @@ If you have been assigned to fix an issue or develop a new feature, please follo
 
 - Fork this repository.
 - Install dependencies by running `$ pnpm install`.
-  - We use [pnpm](https://pnpm.io/) v7 for package management.
+  - We use [pnpm](https://pnpm.io/) v8 for package management.
   - We use [nvm](https://github.com/nvm-sh/nvm) to manage node versions - please make sure to use the version mentioned in `.nvmrc`.
 - Run development server using `pnpm run watch`.
 - Implement your changes and tests to files in the `src/` directory and corresponding test files.