Fix benchmark workflow

Author: willirath

asv_bench/asv.conf.json

@@ -31,7 +31,7 @@
   ],
   // List of branches to benchmark. If not provided, defaults to "master"
   // (for git) or "default" (for mercurial).
-  "branches": ["master"], // for git
+  "branches": ["main"], // for git
   // "branches": ["default"],    // for mercurial
 
   // The DVCS being used.  If not set, it will be automatically