`gofmt` check fails if `go.mod` and `go.sum` are not in the root directory

**Describe the bug**
The `gofmt` check fails if Go code is stored in a subdirectory of the repository:

```
gofmt....................................................................Failed
- hook id: gofmt
- exit code: 1

go: cannot find main module, but found .git/config in /Users/gchappel/code/sample-directory
to create a module there, run:
go mod init
```

**To Reproduce**
* Create an empty directory
* `git init .`
* Configure `.pre-commit-config.yaml` with the Gruntwork pre-commit repo and enable the `gofmt` hook
* Create a subdirectory
* In this subdirectory run `go mod init test`
* In the subdirectory write a deliberately-malformed Go file, for example using spaces instead of tabs:
```go
package main

import (
"fmt" // this line starts with two spaces
)

func main() {
fmt.Println("test") // this line starts with two spaces
}
```
* `git add .` to add the Go code and the `.pre-commit-config.yaml` to the staging area
* run `pre-commit run gofmt`
* see error

**Expected behavior**
The malformed Go file has its spaces replaced with tabs

**Nice to have**
- [ ] Terminal output
- [ ] Screenshots

**Additional context**
Add any other context about the problem here.