deps: update various dependencies

We also increase the MSRV to 1.32, the current stable release, which sets
the stage for migrating to Rust 2018.

grep-matcher/Cargo.toml

@@ -14,10 +14,10 @@ license = "Unlicense/MIT"
 autotests = false
 
 [dependencies]
-memchr = "2.0.2"
+memchr = "2.1"
 
 [dev-dependencies]
-regex = "1.0.5"
+regex = "1.1"
 
 [[test]]
 name = "integration"