delete all duplicate empty blanks (#5758)

Signed-off-by: Xiang Dai <764524258@qq.com>

csharp/src/Google.Protobuf/FieldCodec.cs

diff --git a/csharp/src/Google.Protobuf/FieldCodec.cs b/csharp/src/Google.Protobuf/FieldCodec.cs
index 221ad5f..0610521 100644
--- a/csharp/src/Google.Protobuf/FieldCodec.cs
+++ b/csharp/src/Google.Protobuf/FieldCodec.cs
@@ -292,7 +292,7 @@
 
             /// <summary>
             /// Returns a field codec which effectively wraps a value of type T in a message.
-            /// 
+            ///
             /// </summary>
             internal static FieldCodec<T> GetCodec<T>()
             {
@@ -431,7 +431,7 @@
         internal T DefaultValue { get; }
 
         private readonly int tagSize;
-        
+
         internal FieldCodec(
                 Func<CodedInputStream, T> reader,
                 Action<CodedOutputStream, T> writer,