Update default branch in publish-oss.yml (#1318)

Author: colin-rogers-dbt

.github/workflows/publish-oss.yml

@@ -23,7 +23,8 @@ on:
             branch:
                 description: "Choose the branch to publish from"
                 type: string
-                default: "main"
+                # generally all OSS post-prod releases should be off of stable
+                default: "stable"
             version:
                 description: "Choose the version to bump to (e.g. 1.2.3rc1, patch, release) or leave empty"
                 type: string