feat: prevent git from asking for credentials

If you run a git command with GIT_TERMINAL_PROMPT=0, then git will throw
an error rather than prompt the user for a username or password. This is
the behavior that I want for the tool.

https://git-scm.com/docs/git#Documentation/git.txt-codeGITTERMINALPROMPTcode

internal/cli/clone.go

@@ -65,6 +65,9 @@ func (app *App) clone(repo Repo, ch chan<- result) {
 	}
 	args := []string{"clone", "--mirror", repo.URL, repo.Name}
 	cmd := exec.Command("git", args...)
+	noGitPrompt := "GIT_TERMINAL_PROMPT=0"
+	env := append(os.Environ(), noGitPrompt)
+	cmd.Env = env
 	cmd.Dir = filepath.Join(app.HomeDir, defaultStorage)
 	err := cmd.Run()
 	if err != nil {

internal/cli/update.go

@@ -2,6 +2,7 @@ package cli
 
 import (
 	"fmt"
+	"os"
 	"os/exec"
 	"path/filepath"
 
@@ -54,6 +55,9 @@ func (app *App) update(repo Repo, ch chan<- result) {
 
 	args := []string{"remote", "update"}
 	cmd := exec.Command("git", args...)
+	noGitPrompt := "GIT_TERMINAL_PROMPT=0"
+	env := append(os.Environ(), noGitPrompt)
+	cmd.Env = env
 	cmd.Dir = repoDir
 	err = cmd.Run()
 	if err != nil {