Update to 3.1.100 rtm sdk (#7942)

mmitche · brettfo · commit 32b12496654e · 2019-12-09T10:33:43.000-08:00
diff --git a/global.json b/global.json
@@ -1,6 +1,6 @@
 {
   "tools": {
-    "dotnet": "3.0.101",
+    "dotnet": "3.1.100",
     "vs": {
       "version": "16.3",
       "components": [
