Revert "Regex implements pattern, let's use that"

This reverts commit bf87200.

Pattern is unstable.

Author: sgrif

diesel_cli/Cargo.toml

@@ -20,7 +20,7 @@ dotenv = "0.8.0"
 
 [dev-dependencies]
 tempdir = "0.3.4"
-regex = { version = "0.1.48", features = ["pattern"] }
+regex = "0.1.48"
 
 [features]
 postgres = ["diesel/postgres"]

diesel_cli/tests/migrations.rs

@@ -17,7 +17,7 @@ Creating migrations/\\d{14}_hello/up.sql
 Creating migrations/\\d{14}_hello/down.sql\
         ").unwrap();
     assert!(result.is_success());
-    assert!(result.stdout().contains(&expected_stdout));
+    assert!(expected_stdout.is_match(result.stdout()));
 
     let migrations = p.migrations();
     assert_eq!(1, migrations.len());