fix: remove legacy markdownlint tool pin

Signed-off-by: Gregor Zeitlinger <gregor.zeitlinger@grafana.com>

Author: zeitlinger

mise.toml

@@ -10,7 +10,6 @@ editorconfig-checker = "3.6.1"
 "github:grafana/flint" = "0.20.4"
 "github:pinterest/ktlint" = "1.8.0"
 lychee = "0.23.0"
-markdownlint-cli2 = "0.22.0"
 "pipx:codespell" = "2.4.2"
 rumdl = "0.1.80"
 shellcheck = "0.11.0"