fix: use git changelog to avoid GitHub compare API dependency

Switching from use: github to use: git means GoReleaser reads the
changelog from git log directly, so deleted previous tags don't
cause a 404 on the GitHub compare endpoint.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: bschellenberger2600

.goreleaser.stable.yaml

@@ -79,7 +79,7 @@ snapshot:
 
 changelog:
   sort: asc
-  use: github
+  use: git
   filters:
     exclude:
       - "^docs:"

.goreleaser.yaml

@@ -59,7 +59,7 @@ snapshot:
 
 changelog:
   sort: asc
-  use: github
+  use: git
   filters:
     exclude:
       - "^docs:"