Add TruffleRuby 20.3.0

Author: eregon

README.md

@@ -16,7 +16,7 @@ This action currently supports these versions of MRI, JRuby and TruffleRuby:
 | ----------- | -------- |
 | Ruby | 2.1.9, 2.2, 2.3.0 - 2.3.8, 2.4.0 - 2.4.10, 2.5.0 - 2.5.8, 2.6.0 - 2.6.6, 2.7.2, head, debug, mingw, mswin |
 | JRuby | 9.1.17.0, 9.2.9.0 - 9.2.13.0, head |
-| TruffleRuby | 19.3.0 - 20.2.0, head |
+| TruffleRuby | 19.3.0 - 20.3.0, head |
 
 `ruby-debug` is the same as `ruby-head` but with assertions enabled (`-DRUBY_DEBUG=1`).  
 On Windows, `mingw` and `mswin` are `ruby-head` builds using the MSYS2/MinGW and the MSVC toolchains respectively.

dist/index.js

@@ -18,7 +18,7 @@ export function getVersions(platform) {
     ],
     "truffleruby": [
       "19.3.0", "19.3.1",
-      "20.0.0", "20.1.0", "20.2.0",
+      "20.0.0", "20.1.0", "20.2.0", "20.3.0",
       "head"
     ]
   }