Moving Java 19 to 20 and adding Alpine (#2162)

.github/workflows/build-multiarch.yml

@@ -18,7 +18,8 @@ jobs:
       matrix:
         # NOTE: the "latest" variant is identified in the Docker meta step's 'latest' config
         variant:
-          - java19
+          - java20
+          - java20-alpine
           - java17
           - java17-graalvm-ce
           - java17-jdk
@@ -33,11 +34,15 @@ jobs:
           - java11-openj9
           - java11-jdk
         include:
-        # JAVA 19:
-          - variant: java19
-            baseImage: eclipse-temurin:19-jre-focal
+        # JAVA 20:
+          - variant: java20
+            baseImage: eclipse-temurin:20-jre
             platforms: linux/amd64,linux/arm/v7,linux/arm64
             mcVersion: 1.19.3
+          - variant: java20-alpine
+            baseImage: eclipse-temurin:20-jre-alpine
+            platforms: linux/amd64
+            mcVersion: 1.19.3
         # JAVA 17:
           - variant: java17
             # jammy doesn't work until minecraft updates to https://github.com/netty/netty/issues/12343

.github/workflows/verify-pr.yml

@@ -16,10 +16,16 @@ jobs:
       fail-fast: false
       matrix:
         variant:
+          - java20
           - java17
           - java17-alpine
           - java8-multiarch
         include:
+        # JAVA 20:
+          - variant: java20
+            baseImage: eclipse-temurin:20-jre
+            platforms: linux/amd64,linux/arm/v7,linux/arm64
+            mcVersion: 1.19.3
         # JAVA 17:
           - variant: java17
             # jammy doesn't work until minecraft updates to https://github.com/netty/netty/issues/12343