Update opam

Author: toots

packages/duppy/duppy.0.9.3/opam

@@ -3,7 +3,7 @@ opam-version: "2.0"
 synopsis: "Library providing monadic threads"
 maintainer: ["The Savonet Team <[email protected]>"]
 authors: ["Romain Beauxis <[email protected]>"]
-license: "LGPL-2.1"
+license: "LGPL-2.1-only"
 homepage: "https://github.com/savonet/ocaml-duppy"
 bug-reports: "https://github.com/savonet/ocaml-duppy/issues"
 depends: [