Remove unnecessary explicit cast

Remove unnecessary Self declaration.

src/main.zig

@@ -40,14 +40,12 @@ const SaprusMessage = union(SaprusPacketType) {
     file_transfer: void, // unimplemented
     connection: Connection,
 
-    const Self = @This();
-
-    fn toBytes(s: Self, allocator: Allocator) ![]u8 {
+    fn toBytes(self: SaprusMessage, allocator: Allocator) ![]u8 {
         var buf = std.ArrayList(u8).init(allocator);
         const w = buf.writer();
-        try w.writeInt(u16, @intFromEnum(@as(SaprusPacketType, s)), .big);
+        try w.writeInt(u16, @intFromEnum(self), .big);
 
-        switch (s) {
+        switch (self) {
             .relay => |r| {
                 try w.writeStructEndian(r.header, .big);
                 try w.writeInt(u16, @intCast(r.payload.len), .big);