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and delete outdated `bindata` clause in Makefile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, 1 insertions, 1 deletions

diff --git a/Dockerfile b/Dockerfile
index b634ed1..1198370 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -1,4 +1,4 @@
-FROM golang:1.17
+FROM golang:1.18
 
 EXPOSE 8080
 RUN \