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>

tests/main.js

@@ -38,6 +38,8 @@ so0tiQKBgGQXZaxaXhYUcxYHuCkQ3V4Vsj3ezlM92xXlP32SGFm3KgFhYy9kATxw
 Cax1ytZzvlrKLQyQFVK1COs2rHt7W4cJ7op7C8zXfsigXCiejnS664oAuX8sQZID
 x3WQZRiXlWejSMUAHuMwXrhGlltF3lw83+xAjnqsVp75kGS6OH61
 -----END RSA PRIVATE KEY-----`,
+  // The Actions runner sets all inputs to empty strings if not set.
+  "INPUT_PERMISSION-ADMINISTRATION": "",
 };
 
 export async function test(cb = (_mockPool) => {}, env = DEFAULT_ENV) {
@@ -61,7 +63,7 @@ export async function test(cb = (_mockPool) => {}, env = DEFAULT_ENV) {
   const owner = env.INPUT_OWNER ?? env.GITHUB_REPOSITORY_OWNER;
   const currentRepoName = env.GITHUB_REPOSITORY.split("/")[1];
   const repo = encodeURIComponent(
-    (env.INPUT_REPOSITORIES ?? currentRepoName).split(",")[0],
+    (env.INPUT_REPOSITORIES ?? currentRepoName).split(",")[0]
   );
 
   mockPool
@@ -77,7 +79,7 @@ export async function test(cb = (_mockPool) => {}, env = DEFAULT_ENV) {
     .reply(
       200,
       { id: mockInstallationId, app_slug: mockAppSlug },
-      { headers: { "content-type": "application/json" } },
+      { headers: { "content-type": "application/json" } }
     );
 
   // Mock installation access token request
@@ -98,7 +100,7 @@ export async function test(cb = (_mockPool) => {}, env = DEFAULT_ENV) {
     .reply(
       201,
       { token: mockInstallationAccessToken, expires_at: mockExpiresAt },
-      { headers: { "content-type": "application/json" } },
+      { headers: { "content-type": "application/json" } }
     );
 
   // Run the callback