fix: permission input handling (#243)

This pull request fixes the handling of permissions inputs.

- Updated `getPermissionsFromInputs` in
`lib/get-permissions-from-inputs.js` to use hyphens
(`INPUT_PERMISSION-`) instead of underscores (`INPUT_PERMISSION_`) in
input keys, added a check to skip empty values, and clarified behavior
when no permissions are set.
- Added a `shouldRetry` function to retry requests when server errors
(HTTP status 500 or higher) occur in the `main` function in
`lib/main.js` to prevent unnecessary retries.
- Updated test cases in `tests/main-token-permissions-set.test.js` to
match the new input key format with hyphens.
- Added a default empty string for unset inputs (e.g.,
`INPUT_PERMISSION-ADMINISTRATION`) in `tests/main.js` to simulate the
behavior of the Actions runner.
- Updated snapshots in `tests/snapshots/index.js.md` to reflect the
updated hyphenated input keys in permissions.

---------

Co-authored-by: Gregor Martynus <39992+gr2m@users.noreply.github.com>

lib/get-permissions-from-inputs.js

@@ -7,9 +7,12 @@
  */
 export function getPermissionsFromInputs(env) {
   return Object.entries(env).reduce((permissions, [key, value]) => {
-    if (!key.startsWith("INPUT_PERMISSION_")) return permissions;
+    if (!key.startsWith("INPUT_PERMISSION-")) return permissions;
+    if (!value) return permissions;
 
-    const permission = key.slice("INPUT_PERMISSION_".length).toLowerCase();
+    const permission = key.slice("INPUT_PERMISSION-".length).toLowerCase();
+
+    // Inherit app permissions if no permissions inputs are set
     if (permissions === undefined) {
       return { [permission]: value };
     }

lib/main.js

@@ -89,6 +89,7 @@ export async function main(
           permissions
         ),
       {
+        shouldRetry: (error) => error.status >= 500,
         onFailedAttempt: (error) => {
           core.info(
             `Failed to create token for "${parsedRepositoryNames.join(