Bump to version 3.0.0 (and edition 2021, update authors

Author: burke

Cargo.lock

@@ -1,12 +1,10 @@
 [package]
 name = "shadowenv"
-version = "2.1.2"
+version = "3.0.0"
 authors = [
-    "Burke Libbey <[email protected]>",
-    "Lisa Ugray <[email protected]>",
-    "Aaron Olson <[email protected]>",
+    "Shopify Engineering <[email protected]>",
 ]
-edition = "2018"
+edition = "2021"
 
 [dependencies]
 blake2 = "0.10.6"