Add support for truffleruby-head

Author: eregon

.github/workflows/test.yml

@@ -14,10 +14,12 @@ jobs:
       matrix:
         os: [ ubuntu-16.04, ubuntu-18.04, macos-latest, windows-latest ]
         # Use various version syntaxes here for testing
-        ruby: [ .ruby-version, 2.3, ruby-2.4, 2.5, ruby-2.6.5, 2.7.0, jruby, truffleruby, rubinius ]
+        ruby: [ .ruby-version, 2.3, ruby-2.4, 2.5, ruby-2.6.5, 2.7.0, jruby, truffleruby, truffleruby-head, rubinius ]
         exclude:
         - os: windows-latest
           ruby: truffleruby
+        - os: windows-latest
+          ruby: truffleruby-head
         - os: ubuntu-16.04
           ruby: rubinius
         - os: macos-latest

README.md

@@ -13,7 +13,7 @@ This action currently supports these versions of MRI, JRuby and TruffleRuby:
 | ----------- | -------- |
 | Ruby | 2.3.0 - 2.3.8, 2.4.0 - 2.4.9, 2.5.0 - 2.5.7, 2.6.0 - 2.6.5, 2.7.0 |
 | JRuby | 9.2.9.0 |
-| TruffleRuby | 19.3.0, 19.3.1 |
+| TruffleRuby | 19.3.0, 19.3.1, head |
 | Rubinius | 4.13 |
 
 Note that Ruby 2.3 and the OpenSSL version it needs (1.0.2) are both end-of-life,