Update travis-ci configuraton for Python 3.10 and Java 17.

.travis.yml

@@ -20,34 +20,19 @@ matrix:
     language: python
     python: 3.9
   - os: linux
-    dist: xenial # or later
+    dist: bionic # or later
     language: python
-    python: 3.10
+    python: 3.10.1 # 3.10 doesn't currently work.
   - os: linux
     dist: xenial
     language: java
     jdk: openjdk8
-  - os: linux
-    language: java
-    jdk: openjdk9
-  - os: linux
-    language: java
-    jdk: openjdk10
   - os: linux
     language: java
     jdk: openjdk11
   - os: linux
     language: java
-    jdk: openjdk12
-  - os: linux
-    language: java
-    jdk: openjdk13
-  - os: linux
-    language: java
-    jdk: openjdk14
-  - os: linux
-    language: java
-    jdk: openjdk15
+    jdk: openjdk17
   - os: osx
     language: generic