Merge pull request #247 from commonmark/java-17

Test against Java 17

Author: robinst

.github/workflows/ci.yml

@@ -9,7 +9,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        java: [1.8, 11]
+        java: [1.8, 11, 17]
     steps:
       - name: Checkout sources
         uses: actions/checkout@v2

README.md

@@ -23,7 +23,7 @@ full library with a nice API and the following features:
 * Flexible (manipulate the AST after parsing, customize HTML rendering)
 * Extensible (tables, strikethrough, autolinking and more, see below)
 
-The library is supported on Java 8 and Java 9. It should work on Java 7
+The library is supported on Java 8 or later. It should work on Java 7
 and Android too, but that is on a best-effort basis, please report
 problems. For Android the minimum API level is 19, see the
 [commonmark-android-test](commonmark-android-test) directory.