TUN-6414: Remove go-sumtype from cloudflared build process

This PR removes go-sumtype from cloudflared's build processes.

The value we see from analysing exhaustive match patterns in go is minimal (we can do this in code reviews) compared to using a tool that is unmaintained and (now broken) in Go 1.18.

We'd already been using the patched version here: https://github.com/sudarshan-reddy/go-sumtype because the original is broken for go tools > 1.16

.github/workflows/check.yaml

@@ -12,8 +12,6 @@ jobs:
       uses: actions/setup-go@v2
       with:
         go-version: ${{ matrix.go-version }}
-    - name: Install go-sumtype
-      run: go get github.com/sudarshan-reddy/go-sumtype
     - name: Checkout code
       uses: actions/checkout@v2
     - name: Test

Makefile

@@ -293,11 +293,6 @@ quic-deps:
 .PHONY: vet
 vet:
 	go vet -mod=vendor ./...
-	# go get github.com/sudarshan-reddy/go-sumtype (don't do this in build directory or this will cause vendor issues)
-	# Note: If you have github.com/BurntSushi/go-sumtype then you might have to use the repo above instead
-	# for now because it uses an older version of golang.org/x/tools.
-	which go-sumtype
-	go-sumtype $$(go list -mod=vendor ./...)
 
 .PHONY: goimports
 goimports:

cfsetup.yaml

@@ -153,7 +153,6 @@ stretch: &stretch
       - gotest-to-teamcity
     pre-cache: &test_pre_cache
       - go get golang.org/x/tools/cmd/goimports
-      - go get github.com/sudarshan-reddy/go-sumtype@v0.0.0-20210827105221-82eca7e5abb1
     post-cache:
       - export GOOS=linux
       - export GOARCH=amd64