Add Tausug (tsg) (#284)

Requested at
https://translatewiki.net/w/i.php?oldid=11462618#Request_for_inclusion_of_Tausug_(Sin%C5%ABg)_language_(tsg)

Autonym appears in Ethnologue, and was confirmed
by a native speaker.

Co-authored-by: Abijeet Patro <abijeetpatro@gmail.com>

data/language-data.json

@@ -4366,6 +4366,13 @@
             ],
             "Τσακωνικά"
         ],
+        "tsg": [
+            "Latn",
+            [
+                "AS"
+            ],
+            "Sinūg"
+        ],
         "tt": [
             "Cyrl",
             [
@@ -6128,6 +6135,7 @@
             "war",
             "pam",
             "pag",
+            "tsg",
             "zh-hant",
             "zh",
             "cps",