Support Java 17 (#730)

* Use JDK 17

* Support Java 17

Author: nakamura-to

.github/workflows/ci.yml

@@ -390,7 +390,7 @@ jobs:
         uses: actions/setup-java@v2
         with:
           distribution: 'zulu'
-          java-version: 16
+          java-version: 17
 
       - name: Checkout
         uses: actions/checkout@v2

README.md

@@ -201,5 +201,6 @@ Major versions
 | Java 14 |        |   v    |
 | Java 15 |        |   v    |
 | Java 16 |        |   v    |
+| Java 17 |        |   v    |
 
   [apt]: https://www.jcp.org/en/jsr/detail?id=269