gitleaks: Support stdin (#896)

Author: mosheavni

lua/lint/linters/gitleaks.lua

@@ -4,9 +4,9 @@ local LINTER_NAME = "gitleaks"
 return {
   name = LINTER_NAME,
   cmd = "gitleaks",
-  stdin = false,
+  stdin = true,
   append_fname = true,
-  args = { "--report-format=json", "--report-path=-", "--exit-code=0", "file" },
+  args = { "stdin", "--report-format=json", "--report-path=-", "--exit-code=0" },
   stream = "stdout",
   ignore_exitcode = false,
   parser = function(output, bufnr, _)