Test with go 1.20 and 1.21, lint with 1.21 (#568)

Author: jhump

.circleci/config.yml

@@ -32,7 +32,19 @@ jobs:
   build-1-19:
     working_directory: ~/repo
     docker:
-      - image: cimg/go:1.19
+      - image: cimg/go:1.18
+    steps: *simple_job_steps
+
+  build-1-20:
+    working_directory: ~/repo
+    docker:
+      - image: cimg/go:1.18
+    steps: *simple_job_steps
+
+  build-1-21:
+    working_directory: ~/repo
+    docker:
+      - image: cimg/go:1.21
     steps:
       - checkout
       - restore_cache:
@@ -54,10 +66,10 @@ jobs:
     #- store_test_results:
     #    path: /tmp/test-reports
 
-  build-1-19-u:
+  build-1-21-u:
     working_directory: ~/repo
     docker:
-      - image: cimg/go:1.19
+      - image: cimg/go:1.21
     steps:
       - checkout
       - run:
@@ -75,4 +87,6 @@ workflows:
       # - build-windows
       - build-1-18
       - build-1-19
-      - build-1-19-u
+      - build-1-20
+      - build-1-21
+      - build-1-21-u