Remove dependency on nalgebra macros feature

Remove `nalgebra` `macros` feature from dependencies and add it to dev dependencies.

Bump edition to 2021.

Cargo.toml

@@ -9,7 +9,7 @@ keywords = ["probability", "statistics", "stats", "distribution", "math"]
 categories = ["science"]
 homepage = "https://github.com/statrs-dev/statrs"
 repository = "https://github.com/statrs-dev/statrs"
-edition = "2018"
+edition = "2021"
 
 include = ["CHANGELOG.md", "LICENSE.md", "src/", "tests/"]
 
@@ -19,10 +19,11 @@ path = "src/lib.rs"
 
 [dependencies]
 rand = "0.8"
-nalgebra = { version = "0.32", features = ["rand"] }
+nalgebra = { version = "0.32", default_features = false, features = ["rand", "std"] }
 approx = "0.5.0"
 num-traits = "0.2.14"
 
 [dev-dependencies]
 criterion = "0.3.3"
 anyhow = "1.0"
+nalgebra = { version = "0.32", default_features = false, features = ["macros"] }