fix: git commit date parsing for non-English locales

[GLEF1X]

Fixes #3338

Description:

TruffleHog fails to parse git commit dates when the system locale is non-English (e.g., German outputs Sa. instead of Sat) preventing users from scanning git repos(all git-based sources like local git repo, github, gitlab, etc). This is because the format that is being used --date=format:%a %b %d %H:%M:%S %Y %z is dependent on strftime(3) C library function which is locale dependent(uses POSIX LC_ALL, LC_TIME, LANG). Setting LC_ALL=C or any other locale on the user's side like LC_ALL=de_DE.UTF-8 trufflehog ... doesn't help because the code overwrites the subprocess environment:

trufflehog/pkg/gitparse/gitparse.go

Lines 257 to 273 in 4e02afb

	if err == nil {
	if !isBare {
	cmd.Env = append(cmd.Env, "GIT_DIR="+filepath.Join(absPath, ".git"))
	} else {
	cmd.Env = append(cmd.Env,
	"GIT_DIR="+absPath,
	)
	// We need those variables to handle incoming commits
	// while using trufflehog in pre-receive hooks
	if dir := os.Getenv("GIT_OBJECT_DIRECTORY"); dir != "" {
	cmd.Env = append(cmd.Env, "GIT_OBJECT_DIRECTORY="+dir)
	}
	if dir := os.Getenv("GIT_ALTERNATE_OBJECT_DIRECTORIES"); dir != "" {
	cmd.Env = append(cmd.Env, "GIT_ALTERNATE_OBJECT_DIRECTORIES="+dir)
	}
	}
	}

From os/exec go doc:

// Env specifies the environment of the process.
	// Each entry is of the form "key=value".
	// If Env is nil, the new process uses the current process's
	// environment.
	// If Env contains duplicate environment keys, only the last
	// value in the slice for each duplicate key is used.
	// As a special case on Windows, SYSTEMROOT is always added if
	// missing and not explicitly set to the empty string.
	//
	// See also the Dir field, which may set PWD in the environment.
	Env [][string](https://pkg.go.dev/builtin#string)

This means git only receives GIT_DIR and no locale settings. Rather than fixing env inheritance or adding LC_TIME=C, this PR switches to --date=iso-strict which outputs locale-independent ISO 8601 timestamps (2024-09-28T07:59:21+00:00). I think this is a pretty good solution: iso format has been stable since Git 2.2 (2014), requires no environment manipulation, and uses Go's native time.RFC3339 parser.

Error message when parsing:

2026-01-10T00:28:06-05:00	error	trufflehog	failed to parse commit date	{"source_manager_worker_id": "rc4SK", "unit_kind": "dir", "unit": "/var/folders/hw/r5j4bcyd3472ccwjz0klh5840000gn/T/trufflehog-25309-2688385567", "repo": "file:///Users/xxx/xxx/sample-repo", "commit": "5f506baa305831998a2e15aa07cd381a69fde48f", "latestState": "AuthorDateLine", "error": "parsing time \"Sa. Jan. 10 00:11:44 2026 -0500\" as \"Mon Jan 2 15:04:05 2006 -0700\": cannot parse \"Sa. Jan. 10 00:11:44 2026 -0500\" as \"Mon\""}

Tested on homebrew git on mac(apple git seems to completely ignoring locales) and linux (debian)

Checklist:

• Tests passing (make test-community)?
• Lint passing (make lint this requires golangci-lint)?