Update dependencies (#54)

Update all dependencies,
use Go 1.18 to build and test,
and delete outdated `bindata` clause in Makefile
(we switched to `go:embed` in #50).

Other minor changes:

- Fix the golint import path
  (it switched to golang.org/x/lint long before it was deprecated)
  and fix the failing lint check.
  (Switching from golint to revive is out of scope for this PR.)
- Delete .envrc -- this was transitional for when Go modules were
  optional.

1 files changed, 2 insertions, 2 deletions

diff --git a/tools.go b/tools.go
index 23aa5b2..1b4f8ea 100644
--- a/tools.go
+++ b/tools.go
@@ -1,9 +1,9 @@
+//go:build tools
 // +build tools
 
 package main
 
 import (
-	_ "github.com/go-bindata/go-bindata/go-bindata"
-	_ "github.com/golang/lint/golint"
+	_ "golang.org/x/lint/golint"
 	_ "honnef.co/go/tools/cmd/staticcheck"
 )