Update CI to run against jdk 21 (#581)

Author: testforstephen

.azure-pipelines/signjars-nightly.yml

@@ -46,9 +46,9 @@ extends:
               - checkout: self
                 fetchTags: true
               - task: JavaToolInstaller@0
-                displayName: Use Java 17
+                displayName: Use Java 21
                 inputs:
-                  versionSpec: "17"
+                  versionSpec: "21"
                   jdkArchitectureOption: x64
                   jdkSourceOption: PreInstalled
               - task: CmdLine@2

.azure-pipelines/signjars-rc.yml

@@ -45,9 +45,9 @@ extends:
               - checkout: self
                 fetchTags: true
               - task: JavaToolInstaller@0
-                displayName: Use Java 17
+                displayName: Use Java 21
                 inputs:
-                  versionSpec: "17"
+                  versionSpec: "21"
                   jdkArchitectureOption: x64
                   jdkSourceOption: PreInstalled
               - task: CmdLine@2

.github/workflows/build.yml

@@ -14,10 +14,10 @@ jobs:
     steps:
     - uses: actions/checkout@v2
 
-    - name: Set up JDK 17
+    - name: Set up JDK 21
       uses: actions/setup-java@v1
       with:
-        java-version: '17'
+        java-version: '21'
 
     - name: Cache local Maven repository
       uses: actions/cache@v2
@@ -45,10 +45,10 @@ jobs:
 
     - uses: actions/checkout@v2
 
-    - name: Set up JDK 17
+    - name: Set up JDK 21
       uses: actions/setup-java@v1
       with:
-        java-version: '17'
+        java-version: '21'
 
     - name: Cache local Maven repository
       uses: actions/cache@v2
@@ -71,10 +71,10 @@ jobs:
     steps:
     - uses: actions/checkout@v2
 
-    - name: Set up JDK 17
+    - name: Set up JDK 21
       uses: actions/setup-java@v1
       with:
-        java-version: '17'
+        java-version: '21'
 
     - name: Cache local Maven repository
       uses: actions/cache@v2