The make gen output is not deterministic

[masih]

Reported on Slack:

1 out of ~10 I get this
experiencing backporting over 1.30

diff --git a/api/proxy_gen.go b/api/proxy_gen.go                                                                                                                                                                                                                                                                                                     
index f8c186cd6..06395fea2 100644                                                                                                                                         
--- a/api/proxy_gen.go                                                                                                                                                    
+++ b/api/proxy_gen.go                                                                                                                                                    
@@ -14,7 +14,7 @@ import (                                                                                                                                                
        "github.com/libp2p/go-libp2p/core/network"                                                                                                                        
        "github.com/libp2p/go-libp2p/core/peer"                                                                                                                           
        "github.com/libp2p/go-libp2p/core/protocol"                                                                                                                       
-       "golang.org/x/xerrors"                                                                                                                                            
+       xerrors "golang.org/x/xerrors"                                                                                                                                    
                                                                                                                                                                          
        "github.com/filecoin-project/go-address"                                                                                                                          
        "github.com/filecoin-project/go-bitfield"