build: prep for Go 1.22 by using GOEXPERIMENT=loopvar for tests

In this commit, [we prep for some upcoming changes in
Go](https://go.dev/blog/loopvar-preview) by running our tests with
`GOEXPERIMENT=loopvar`. This changes the loop semantics to fix a common
bug where a scoping issue causes a variable to be re-used, which can
cause unintended bugs down the line.

If everything passes with this flag on, then we can keep it on, and also
rest a bit easier knowing that the compiler will fix a class of bugs
that would previously pop up for us.

.github/workflows/main.yaml

@@ -62,6 +62,9 @@ jobs:
       - name: git checkout
         uses: actions/checkout@v3
 
+      - name: Setup go environment
+        uses: ./.github/actions/setup-go
+
       - name: Run go mod tidy
         run: make mod-check
 

Makefile

@@ -15,7 +15,7 @@ COMMIT := $(shell git describe --tags --dirty)
 
 GOBUILD := GO111MODULE=on go build -v
 GOINSTALL := GO111MODULE=on go install -v
-GOTEST := GO111MODULE=on go test 
+GOTEST := GOEXPERIMENT=loopvar GO111MODULE=on go test 
 GOMOD := GO111MODULE=on go mod
 
 GOLIST := go list -deps $(PKG)/... | grep '$(PKG)'