Bump edition to 2018.

jimblandy · jimblandy · commit 5548686cfe47 · 2019-09-02T18:10:42.000-07:00
diff --git a/Cargo.toml b/Cargo.toml
@@ -2,6 +2,7 @@
 name = "mandelbrot"
 version = "0.2.0"
 authors = ["Jim Blandy <jimb@red-bean.com>"]
+edition = "2018"
 
 [dependencies]
 num = "0.1.34"
