ci: downgrade golang 1.18 → 1.17.8 temporarily until solving "go test requires git due to -buildvcs" backport

- golang/go#51767
- golang/go#51723

> @bcmills requested issue #51723 to be considered for backport to the next 1.18 minor release.
>
> @gopherbot, please backport to Go 1.18. Invoking git for each go test of a package main is surprising and wastes users' time and battery power.

Author: zrma

.github/workflows/ci.yml

@@ -18,7 +18,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        go: [ '1.17', '1.18' ]
+        go: [ '1.17', '1.17.8' ]
     name: action test
     steps:
       - uses: actions/checkout@v2

README.md

@@ -16,7 +16,7 @@
 
 ## Requirement
 
-- [Go](https://golang.org) (v1.18+)
+- [Go](https://golang.org) (v1.17+)
 - [Docker](https://www.docker.com/) (v20.10+)
 
 ## Initialize

go.mod

@@ -1,6 +1,6 @@
 module 1d1go
 
-go 1.18
+go 1.17
 
 replace google.golang.org/grpc => google.golang.org/grpc v1.42.0