Replace go get with go install for gen deps

* Replaces the deprecated `go get` calls with `go install`.

* Add version to pigeon install command
The v1.1.0 release of pigeon was released back in March of 2021 points
to the latest change in the master branch, which was committed over two
years ago. Instead of pulling from master we will pull in the latest
release and update dependenbot to check for this dependency.

* Add github.com/mna/pigeon to dependebot tracking file

Related to: #103

.github/dependabot.yml

@@ -13,5 +13,6 @@ updates:
       - dependency-name: "github.com/hashicorp/packer"
       - dependency-name: "github.com/hashicorp/hcl/v2"
       - dependency-name: "github.com/zclconf/go-cty"
+      - dependency-name: "github.com/mna/pigeon"
     ignore:
       - dependency-name: "github.com/aws/aws-sdk-go"

Makefile

@@ -9,13 +9,9 @@ default: install-build-deps install-gen-deps generate
 ci: testrace ## Test in continuous integration
 
 install-gen-deps: ## Install dependencies for code generation
-	# to avoid having to tidy our go deps, we `go get` our binaries from a temp
-	# dir. `go get` will change our deps and the following deps are not part of
-	# out code dependencies; so a go mod tidy will remove them again. `go
-	# install` seems to install the last tagged version and we want to install
-	# master.
-	@(cd $(TEMPDIR) && GO111MODULE=on go get github.com/mna/pigeon@master)
-	@(cd $(TEMPDIR) && GO111MODULE=on go get github.com/alvaroloes/enumer@master)
+	@go install github.com/mna/pigeon@v1.1.0
+	# Pinning enumer at master branch; the latest tagged release is out of date.
+	@go install github.com/alvaroloes/enumer@master
 
 	@go install github.com/hashicorp/packer-plugin-sdk/cmd/packer-sdc