Add go mod tidy check for Go 1.17

.circleci/config.yml

@@ -77,6 +77,12 @@ jobs:
     steps:
       - install-go-run-tests-windows:
           GOVERSION: "1.17"
+  check-mod-tidy:
+    executor: golang
+    working_directory: /go/src/github.com/hashicorp/packer
+    steps:
+      - checkout
+      - run: go mod tidy -compat=1.17
   check-lint:
     executor: golang
     resource_class: xlarge

.github/CONTRIBUTING.md

@@ -70,7 +70,7 @@ runtime in order to build packer.
 
 1. This project always releases from the latest version of golang.
 [Install go](https://golang.org/doc/install#install) To properly build from
-source, you need to have golang >= v1.16
+source, you need to have golang >= v1.17
 
 ## Setting up Packer for dev