Update version number

Author: KennethTsang

GrowingTextView.podspec

@@ -8,7 +8,7 @@
 
 Pod::Spec.new do |s|
   s.name             = "GrowingTextView"
-  s.version          = "0.5.4"
+  s.version          = "0.5.5"
   s.summary          = "UITextView on Swift 3 and Swift 4. Support auto growing, placeholder and length limit."
 
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