feat: allow repositories input to be comma or newline-separated (#169)

Resolves https://github.com/actions/create-github-app-token/issues/106

- Fixes the parsing to cope with whitespace in the input string.
- Allows the input to be comma or newline-separated. (I've done this for
all array-type inputs in my own actions, but I'm happy to remove this if
you only want to support comma-separated.)
- Added tests for parsing comma and newline-separated inputs.

package-lock.json

@@ -1,12 +1,12 @@
 {
   "name": "create-github-app-token",
-  "version": "1.10.3",
+  "version": "1.10.4",
   "lockfileVersion": 3,
   "requires": true,
   "packages": {
     "": {
       "name": "create-github-app-token",
-      "version": "1.10.3",
+      "version": "1.10.4",
       "license": "MIT",
       "dependencies": {
         "@actions/core": "^1.10.1",