Ignore GC roots directory

PsychoLlama · PsychoLlama · commit f844b6ac5d8a · 2024-04-16T06:52:55.000-04:00
This is defined if you pass `--keep-result` during a Colmena deploy. It
prevents the Nix garbage collector from destroying all your build
results that might've taken FOREVER to compile on a raspi.
diff --git a/.gitignore b/.gitignore
@@ -2,3 +2,4 @@
 .direnv
 result
 result-*
+.gcroots
