Revert "skip builds for 4.7-2020"

This reverts commit cd7c16a.

Author: StephenHodgson

.github/workflows/build-options.json

@@ -5,6 +5,12 @@
     "macos-latest"
   ],
   "unity-version": [
+    "4.7.2",
+    "5.6.7f1 (e80cc3114ac1)",
+    "2017",
+    "2018",
+    "2019",
+    "2020",
     "2021",
     "2022",
     "6000.0",