Add ktx

ktx/external/fmt/.github/pull_request_template.md

@@ -0,0 +1,7 @@
+<!--
+Please read the contribution guidelines before submitting a pull request:
+https://github.com/fmtlib/fmt/blob/master/CONTRIBUTING.md.
+By submitting this pull request, you agree to license your contribution(s)
+under the terms outlined in LICENSE.rst and represent that you have the right
+to do so.
+-->