Removing java-8 from test matrix - upgraded arrow libraries no longer support that jvm version.

Author: cnuernber

.github/workflows/test.yml

@@ -8,7 +8,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        jdk-version: ["8", "11", "17", "21"]
+        jdk-version: ["11", "17", "21"]
     runs-on: ubuntu-22.04
     steps:
     - uses: actions/checkout@v3