Use case-insensitive key comparison for cache keys

bundler.js

@@ -206,7 +206,7 @@ export async function bundleInstall(gemfile, lockFile, platform, engine, rubyVer
   await exec.exec('bundle', ['install', '--jobs', '4'])
 
   // @actions/cache only allows to save for non-existing keys
-  if (cachedKey !== key) {
+  if (!common.isExactCacheKeyMatch(key, cachedKey)) {
     if (cachedKey) { // existing cache but Gemfile.lock differs, clean old gems
       await exec.exec('bundle', ['clean'])
     }

common.js

@@ -412,3 +412,15 @@ export async function setupJavaHome(rubyPrefix) {
     }
   })
 }
+
+// Determines if two keys are an exact match for the purposes of cache matching
+// Specifically, this is a case-insensitive match that ignores accents
+// From actions/cache@v3 src/utils/actionUtils.ts (MIT)
+export function isExactCacheKeyMatch(key, cacheKey) {
+  return !!(
+      cacheKey &&
+      cacheKey.localeCompare(key, undefined, {
+          sensitivity: 'accent'
+      }) === 0
+  );
+}