chore: upgrade Go to 1.25

[matifali]

Summary

• Bumps go directive in go.mod from 1.24.6 to 1.25
• Updates go-version in test.yml and release.yml to match
• Unblocks build(deps): Bump github.com/hashicorp/terraform-plugin-sdk/v2 from 2.38.1 to 2.40.0 #487 and build(deps): Bump golang.org/x/mod from 0.33.0 to 0.34.0 #488

Using minor-only versioning so the toolchain automatically picks up the latest patch release.

[johnstcn]

Auto-updating minor PATCH version is probably fine 👍

[matifali]

Auto-updating minor version is probably fine 👍

I assume you mean patch.