fix(collapse): export pfe-collapse-panel.js

Author: bennypowers

.changeset/stupid-dolphins-compare.md

@@ -0,0 +1,5 @@
+---
+"@patternfly/pfe-collapse": patch
+---
+
+Export `pfe-collapse-panel.js` from package.json

elements/pfe-collapse/package.json

@@ -9,6 +9,7 @@
   "module": "./pfe-collapse.js",
   "exports": {
     ".": "./pfe-collapse.js",
+    "./pfe-collapse-panel.js": "./pfe-collapse-panel.js",
     "./*": "./*.js"
   },
   "publishConfig": {