chore: add PRs welcome badge

Author: codepunkt

README.md

@@ -3,7 +3,8 @@
 <div align="center">
   <h1>vitest-environment-prisma-postgres</h1>
   <a href="https://www.npmjs.com/package/vitest-environment-prisma-postgres"><img src="https://img.shields.io/npm/v/vitest-environment-prisma-postgres.svg?style=flat" /></a>
-  <a href="https://github.com/prisma/prisma/blob/main/LICENSE"><img src="https://img.shields.io/badge/license-MIT-blue" /></a>
+  <a href="https://github.com/codepunkt/vitest-environment-prisma-postgres/blob/main/.github/CONTRIBUTING.md"><img src="https://img.shields.io/badge/PRs-welcome-brightgreen.svg" /></a>
+  <a href="https://github.com/codepunkt/vitest-environment-prisma-postgres/blob/main/LICENSE"><img src="https://img.shields.io/badge/license-MIT-blue" /></a>
   <br />
   <br />
   <a href="#features">Features</a>
@@ -163,4 +164,4 @@ Adding "vitest-environment-prisma-postgres" to `compilerOptions.types` ensures t
 
 ## License
 
-MIT
+MIT