[gftools-packager] Gluten: Version 1.300 added (#4716)

* Gluten Version 1.300 taken from the upstream repo https://github.com/Etcetera-Type-Co/Gluten at commit c8525e6a8d.

ofl/gluten/METADATA.pb

@@ -7,7 +7,7 @@ fonts {
   name: "Gluten"
   style: "normal"
   weight: 400
-  filename: "Gluten[wght].ttf"
+  filename: "Gluten[slnt,wght].ttf"
   post_script_name: "Gluten-Thin"
   full_name: "Gluten Thin"
   copyright: "Copyright 2020 The Gluten Project Authors (https://github.com/Etcetera-Type-Co/Gluten)"
@@ -16,8 +16,17 @@ subsets: "latin"
 subsets: "latin-ext"
 subsets: "menu"
 subsets: "vietnamese"
+axes {
+  tag: "slnt"
+  min_value: -13.0
+  max_value: 13.0
+}
 axes {
   tag: "wght"
   min_value: 100.0
   max_value: 900.0
 }
+source {
+  repository_url: "https://github.com/Etcetera-Type-Co/Gluten"
+  commit: "c8525e6a8d31dde1795485cc66f622beed3e5e80"
+}

ofl/gluten/upstream.yaml

@@ -1,5 +1,5 @@
+archive:
 branch: master
 files:
   OFL.txt: OFL.txt
-  fonts/variable/Gluten[wght].ttf: Gluten[wght].ttf
-repository_url: https://github.com/Etcetera-Type-Co/Gluten
+  fonts/variable/Gluten[slnt,wght].ttf: Gluten[slnt,wght].ttf