[CodeCompletion] Increment on-disc code completion cache version

Author: rintaro

lib/IDE/CodeCompletionCache.cpp

@@ -104,7 +104,7 @@ CodeCompletionCache::~CodeCompletionCache() {}
 /// This should be incremented any time we commit a change to the format of the
 /// cached results. This isn't expected to change very often.
 static constexpr uint32_t onDiskCompletionCacheVersion =
-    11; // Added macro roles
+    12; // Removed 'IsAsync'.
 
 /// Deserializes CodeCompletionResults from \p in and stores them in \p V.
 /// \see writeCacheModule.