update actions to resolve deprecation warnings, and bump OS version
diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index 2bc6cc0..64bacb7 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -4,15 +4,15 @@
 
 jobs:
   build:
-    runs-on: ubuntu-20.04
+    runs-on: ubuntu-22.04
     strategy:
       fail-fast: false
       matrix:
         java: [ 8, 11, 17, 21 ]
 
     steps:
-      - uses: actions/checkout@v3
-      - uses: actions/cache@v3
+      - uses: actions/checkout@v4
+      - uses: actions/cache@v4
         with:
           path: ~/.m2/repository
           key: ${{ runner.os }}-maven-${{ hashFiles('**/pom.xml') }}
@@ -20,7 +20,7 @@
             ${{ runner.os }}-maven-
 
       - name: Install JDK ${{ matrix.java }}
-        uses: actions/setup-java@v3
+        uses: actions/setup-java@v4
         with:
           java-version: ${{ matrix.java }}
           distribution: 'temurin'