.mailmap: add an alias for Nicholas Bishop

Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/1999>
diff --git a/.mailmap b/.mailmap
index 009d3e6..2566ad7 100644
--- a/.mailmap
+++ b/.mailmap
@@ -441,6 +441,8 @@
 Nian Wu <nian.wu@intel.com> <nian@graphics.(none)>
 Nian Wu <nian.wu@intel.com> <nian@tinderbox.sh.intel.com>
 
+Nicholas Bishop <nbishop@neverware.com> <nicholasbishop@gmail.com>
+
 Nick Bowler <nbowler@draconx.ca>
 
 Nick Sarnie <commendsarnex@gmail.com>