Update type definition for spdx-satisfies

I have a PR in with DefinitelyTyped, but this change should allow CI
to pass while that goes through the process.

src/spdx-satisfies.d.ts

@@ -0,0 +1,4 @@
+declare module 'spdx-satisfies' {
+  function spdxSatisfies(candidate: string, allowList: string[]): boolean
+  export = spdxSatisfies
+}