Add categories cargo metadata (#435)

Author: CosmicHorrorDev

Cargo.toml

@@ -9,6 +9,7 @@ rust-version = "1.51.0"
 homepage = "https://insta.rs/"
 repository = "https://github.com/mitsuhiko/insta"
 keywords = ["snapshot", "testing", "jest", "approval"]
+categories = ["development-tools::testing"]
 readme = "README.md"
 exclude = [
     "assets/*"

cargo-insta/Cargo.toml

@@ -8,6 +8,7 @@ homepage = "https://insta.rs/"
 repository = "https://github.com/mitsuhiko/insta"
 documentation = "https://insta.rs/docs/cli/"
 keywords = ["snapshot", "testing", "jest"]
+categories = ["development-tools::cargo-plugins"]
 edition = "2018"
 readme = "README.md"