[Workflows] cla.yaml references incorrect repo branch for the CLA document

[FelixWolf]

Environment

N/A

Description

Workflow currently references master instead of main for it's sourcing of the contributor license agreement. This may cause issues if the CLA is updated in the main (Default) repository, where the CLA bot will incorrectly reference a old version.
See: https://github.com/secondlife/viewer/blob/7507abb566fe90fb96f866418d68a3635baf9806/.github/workflows/cla.yaml#L22C11-L22C81

Reproduction steps

N/A

[FelixWolf]

I'd create a PR for this but I don't want to mess up the CLA workflow by accident, considering it is important. I'd rather let someone who knows what they are doing change it.

[kylelinden]

@vir-linden please update appropriate milestone.

[vir-linden]

Fix has been merged to main