chore: bump @workos/oagen to ^0.15.0 (#77)

oagen 0.13/0.14/0.15 ship the rename-detection passes that downgrade
type/enum renames from breaking to soft-risk in compat reports
(workos/oagen #49, #51, #53). Until this bump, downstream consumers
that pull oagen-emitters still resolve to oagen 0.12.0 nested under
node_modules/@workos/oagen-emitters/node_modules — so the new
extractor + differ logic never runs and breaking-changes reports stay
unchanged from pre-0.13 behaviour.

Verified: workos/openapi-spec#17 currently shows breaking=11 because
oagen-emitters is pinned to ^0.12.0; after this bump and an
oagen-emitters release, the same diff drops to breaking=0 across all
five languages (validated locally by re-extracting + re-diffing each
SDK with oagen 0.15.0).

All 399 tests pass.

Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: gjtorikian

package-lock.json

@@ -54,6 +54,6 @@
     "node": ">=24.10.0"
   },
   "dependencies": {
-    "@workos/oagen": "^0.12.0"
+    "@workos/oagen": "^0.15.0"
   }
 }