chore: Add Rust 2018 edition tag to .rustfmt.toml (#3120)

bruceg · web-flow · commit ed9006f78344 · 2020-07-20T15:38:34.000-06:00
Some editors use `rustfmt` directly instead of `cargo fmt`, which
requires explicitly indicating which Rust edition the project is using.

Signed-off-by: Bruce Guenter &lt;bruce@timber.io&gt;
diff --git a/.rustfmt.toml b/.rustfmt.toml
@@ -2,3 +2,4 @@
 # Not stable yet.
 # indent_style = "Block"
 reorder_imports = true
+edition = "2018"
