[CI] Lock syntax test runner to build 4183 (#4107)

Workaround for sublimehq/sublime_text#6539
until it is fixed upstream.

.github/workflows/ci.yml

@@ -50,12 +50,17 @@ jobs:
           #   sublime-build: 4169
           #   optional: true
 
-          # latest dev build
-          # https://www.sublimetext.com/dev
+          # latest working dev build
           - sublime-channel: dev
-            sublime-build: latest
+            sublime-build: 4183
             optional: false
 
+          # latest dev build
+          # https://www.sublimetext.com/dev
+          # - sublime-channel: dev
+          #   sublime-build: latest
+          #   optional: false
+
     steps:
 
       # https://github.com/actions/checkout