Bump security-framework from 2.1.1 to 2.1.2

security-framework=2.1.1 doesn't build on Darwin 10.12.
https://github.com/kornelski/rust-security-framework/issues/124

--- i/Cargo.lock
+++ w/Cargo.lock
@@ -1361,9 +1361,9 @@ checksum = "d29ab0c6d3fc0ee92fe66e2d99f700eab17a8d57d1c1d3b748380fb20baa78cd"
 
 [[package]]
 name = "security-framework"
-version = "2.1.1"
+version = "2.1.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "2dfd318104249865096c8da1dfabf09ddbb6d0330ea176812a62ec75e40c4166"
+checksum = "d493c5f39e02dfb062cd8f33301f90f9b13b650e8c1b1d0fd75c19dd64bff69d"
 dependencies = [
  "bitflags",
  "core-foundation",