test: fix test file extensions and inputs for repositories (#161)

This pull request fixes the file extension for two test files that were
incorrectly named. This caused them not to be tested. A new test has
been added to ensure all test files have the correct extension.

This also fixes a bug in some tests where `repositories` inputs included
the repository owner. The owner has been removed from these inputs and
the snapshots have been updated.

tests/main-private-key-with-escaped-newlines.test.js

@@ -0,0 +1,9 @@
+import { DEFAULT_ENV, test } from "./main.js";
+
+// Verify `main` works correctly when `private-key` input has escaped newlines
+await test(() => {
+  process.env["INPUT_PRIVATE-KEY"] = DEFAULT_ENV["INPUT_PRIVATE-KEY"].replace(
+    /\n/g,
+    "\\n"
+  );
+});