Gin some test failed on v1.7.7 tags & go1.17

git checkout v1.7.7
go test ./...

Description

## Expectations

all passed

## Actual result

```bash
=== RUN   TestContextRenderFile
    context_test.go:1008: 
            Error Trace:    context_test.go:1008
            Error:          Not equal: 
                            expected: "text/plain; charset=utf-8"
                            actual  : "text/x-go; charset=utf-8"

                            Diff:
                            --- Expected
                            +++ Actual
                            @@ -1 +1 @@
                            -text/plain; charset=utf-8
                            +text/x-go; charset=utf-8
            Test:           TestContextRenderFile
--- FAIL: TestContextRenderFile (0.00s)


Expected :text/plain; charset=utf-8
Actual   :text/x-go; charset=utf-8

=== RUN   TestContextRenderFileFromFS
    context_test.go:1020: 
            Error Trace:    context_test.go:1020
            Error:          Not equal: 
                            expected: "text/plain; charset=utf-8"
                            actual  : "text/x-go; charset=utf-8"

                            Diff:
                            --- Expected
                            +++ Actual
                            @@ -1 +1 @@
                            -text/plain; charset=utf-8
                            +text/x-go; charset=utf-8
            Test:           TestContextRenderFileFromFS
--- FAIL: TestContextRenderFileFromFS (0.00s)


Expected :text/plain; charset=utf-8
Actual   :text/x-go; charset=utf-8

Environment

• go version: go version go1.17.3 linux/amd64
• gin version (or commit ref): v1.7.7
• operating system:

maybe missed https://github.com/gin-gonic/gin/commit/77649bcfee1a3eef1cc79839457ed5369916edb4 on v1.7.7

Comment From: Bisstocuz

@thinkerou

Comment From: thinkerou

1. https://github.com/gin-gonic/gin/pull/2952 test ok
2. on my mac, run make test ok
3. on my mac, run go test ./... ok

➜  gin-1.7.7 go test ./...
ok      github.com/gin-gonic/gin    1.102s
ok      github.com/gin-gonic/gin/binding    0.441s
?       github.com/gin-gonic/gin/ginS   [no test files]
ok      github.com/gin-gonic/gin/internal/bytesconv 0.437s
?       github.com/gin-gonic/gin/internal/json  [no test files]
ok      github.com/gin-gonic/gin/render 0.845s

Comment From: WangLeonard

@thinkerou Hi, This test case can indeed be passed on the mac.
I reproduced it on linux.
And $GOROOT/src/mime/type.go TypeByExtension will be different return value on linux and mac
mac

linux

I'm not sure about the further reason for this. My environment problem or go problem or gin problem.

Comment From: shawndx

Thought it's related to a go sdk change, https://go-review.googlesource.com/c/go/+/305230, which supports "Shared MIME-info Database on Unix systems" in go1.17