Catch error.BrokenPipe and close connection

Users have reported this error occurring occasionally, close connection
and continue processing requests when it occurs.

src/jetzig/http/Server.zig

@@ -312,6 +312,7 @@ fn isBadHttpError(err: anyerror) bool {
         error.MissingFinalNewline,
         error.HttpConnectionClosing,
         error.ConnectionResetByPeer,
+        error.BrokenPipe,
         => true,
         else => false,
     };