chore: exit changeset prerelease mode for the 4.5.0 release (triggerdotdev#4099)

Takes changesets out of rc prerelease mode so the next version bump
produces the stable 4.5.0 GA release rather than another release
candidate.

Author: ericallam

.changeset/pre.json

@@ -1,5 +1,5 @@
 {
-  "mode": "pre",
+  "mode": "exit",
   "tag": "rc",
   "initialVersions": {
     "coordinator": "0.0.1",