Add golang package mirroring

[mxr]

Tested as follows:

Set up folders:

$ mkdir gofumpt
$ cd gofumpt
$ git init
Initialized empty Git repository in /Users/mxr/tmp/gofumpt/.git/

Make the mirror:

$ pre-commit-mirror . --language=golang --package-name=mvdan.cc/gofumpt --types=go --entry=gofumpt --args='-w'
[main (root-commit) cc51955] Mirror: v0.1.0
 6 files changed, 36 insertions(+)
 create mode 100644 .pre-commit-hooks.yaml
 create mode 100644 .version
 create mode 100644 LICENSE
 create mode 100644 go.mod
 create mode 100644 go.sum
 create mode 100644 main.go
[main ab11896] Mirror: v0.1.1
 2 files changed, 2 insertions(+), 2 deletions(-)
[main 629ac14] Mirror: v0.2.0
 2 files changed, 2 insertions(+), 2 deletions(-)
[main 7708360] Mirror: v0.2.1
 2 files changed, 2 insertions(+), 2 deletions(-)
[main 85d45b4] Mirror: v0.3.0
 2 files changed, 2 insertions(+), 2 deletions(-)
[main 3f61fe3] Mirror: v0.3.1
 2 files changed, 2 insertions(+), 2 deletions(-)
[main 01fadcb] Mirror: v0.4.0
 2 files changed, 2 insertions(+), 2 deletions(-)
[main 81f7cc6] Mirror: v0.5.0
 2 files changed, 2 insertions(+), 2 deletions(-)
[main 7e69c0e] Mirror: v0.6.0
 2 files changed, 2 insertions(+), 2 deletions(-)
[main eddc737] Mirror: v0.7.0
 2 files changed, 2 insertions(+), 2 deletions(-)
[main 0c15eda] Mirror: v0.8.0
 2 files changed, 2 insertions(+), 2 deletions(-)
[main 5068572] Mirror: v0.9.0
 2 files changed, 2 insertions(+), 2 deletions(-)
[main 1b4f0e2] Mirror: v0.9.1
 2 files changed, 2 insertions(+), 2 deletions(-)
[main ddfa8cd] Mirror: v0.9.2
 2 files changed, 2 insertions(+), 2 deletions(-)
$ cat .pre-commit-hooks.yaml 
-   id: gofumpt
    name: mvdan.cc/gofumpt
    description: ''
    entry: gofumpt
    language: golang
    'types': [go]
    args: ["-w"]
    require_serial: false
    additional_dependencies: ["mvdan.cc/[email protected]"]
    minimum_pre_commit_version: '0'

Now testing the hook by creating a file with badly formatted golan code and running gofumpt on it:

$ echo "package main\nfunc main(    ){}\n" > main.go
$ cat main.go                                       
package main
func main(    ){}

$ git add -u && git commit -m 'file with bad whitespace'
[main d5af592] file with bad whitespace
 1 file changed, 1 insertion(+), 1 deletion(-)
$ pre-commit try-repo . gofumpt --files main.go
===============================================================================
Using config:
===============================================================================
repos:
-   repo: .
    rev: d5af5923ed6f3b889f9bd7bf3d270fc4d3c99a2f
    hooks:
    -   id: gofumpt
===============================================================================
[INFO] Initializing environment for ..
[INFO] Initializing environment for .:mvdan.cc/[email protected].
[INFO] Installing environment for ..
[INFO] Once installed this environment will be reused.
[INFO] This may take a few minutes...
mvdan.cc/gofumpt.........................................................Failed
- hook id: gofumpt
- files were modified by this hook
$ cat main.go 
package main

func main() {}

[mxr]

Think this works but trying to figure out the right invocation of pre-commit-mirror before marking as 'ready to review'

[mxr]

OK got it