[C#] Remove superfluous semicolon in C# structs (#6791)

Aims to resolve #6788

-Remove superfluous semicolon in C# structs

tests/namespace_test/NamespaceA/NamespaceB/StructInNestedNS.cs

@@ -43,7 +43,7 @@ public struct StructInNestedNS : IFlatbufferObject
       _o.A,
       _o.B);
   }
-};
+}
 
 public class StructInNestedNST
 {

tests/namespace_test/NamespaceA/NamespaceB/TableInNestedNS.cs

@@ -49,7 +49,7 @@ public struct TableInNestedNS : IFlatbufferObject
       builder,
       _o.Foo);
   }
-};
+}
 
 public class TableInNestedNST
 {

tests/namespace_test/NamespaceA/SecondTableInA.cs

@@ -49,7 +49,7 @@ public struct SecondTableInA : IFlatbufferObject
       builder,
       _refer_to_c);
   }
-};
+}
 
 public class SecondTableInAT
 {

tests/namespace_test/NamespaceA/TableInFirstNS.cs

@@ -83,7 +83,7 @@ public struct TableInFirstNS : IFlatbufferObject
       _foo_union,
       _o.FooStruct);
   }
-};
+}
 
 public class TableInFirstNST
 {