[triplet] Remove obsolete check about dash in the name

Triplets haven't required that for a while now

toolsrc/src/vcpkg/triplet.cpp

@@ -41,9 +41,6 @@ namespace vcpkg
     Triplet Triplet::from_canonical_name(const std::string& triplet_as_string)
     {
         std::string s(Strings::ascii_to_lowercase(triplet_as_string));
-        const auto it = std::find(s.cbegin(), s.cend(), '-');
-        Checks::check_exit(VCPKG_LINE_INFO, it != s.cend(), "Invalid triplet: %s", triplet_as_string);
-
         const auto p = g_triplet_instances.emplace(std::move(s));
         return &*p.first;
     }