Fix go reference link

Fixes the link as reported here:
https://gophers.slack.com/archives/CAK2124AG/p1740580561980929

Author: kevmo314

README.md

@@ -10,7 +10,7 @@
   <a href="https://pion.ly/slack"><img src="https://img.shields.io/badge/join-us%20on%20slack-gray.svg?longCache=true&logo=slack&colorB=brightgreen" alt="Slack Widget"></a>
   <br>
   <img alt="GitHub Workflow Status" src="https://img.shields.io/github/actions/workflow/status/pion/sdp/test.yaml">
-  <a href="https://pkg.go.dev/github.com/pion/sdp/v2"><img src="https://pkg.go.dev/badge/github.com/pion/sdp/v2.svg" alt="Go Reference"></a>
+  <a href="https://pkg.go.dev/github.com/pion/sdp/v3"><img src="https://pkg.go.dev/badge/github.com/pion/sdp/v3.svg" alt="Go Reference"></a>
   <a href="https://codecov.io/gh/pion/sdp"><img src="https://codecov.io/gh/pion/sdp/branch/master/graph/badge.svg" alt="Coverage Status"></a>
   <a href="https://goreportcard.com/report/github.com/pion/sdp"><img src="https://goreportcard.com/badge/github.com/pion/sdp" alt="Go Report Card"></a>
   <a href="LICENSE"><img src="https://img.shields.io/badge/License-MIT-yellow.svg" alt="License: MIT"></a>
@@ -32,4 +32,4 @@ If you need commercial support or don't want to use public methods you can conta
 Check out the [contributing wiki](https://github.com/pion/webrtc/wiki/Contributing) to join the group of amazing people making this project possible
 
 ### License
-MIT License - see [LICENSE](LICENSE) for full text
+MIT License - see [LICENSE](LICENSE) for full text