Bump markdownlint-cli from 0.11.0 to 0.12.0 (exonum#833)

Bumps [markdownlint-cli](https://github.com/igorshubovych/markdownlint-cli) from 0.11.0 to 0.12.0.
- [Release notes](https://github.com/igorshubovych/markdownlint-cli/releases)
- [Commits](igorshubovych/markdownlint-cli@v0.11.0...v0.12.0)

Signed-off-by: dependabot[bot] <support@dependabot.com>

package.json

@@ -6,7 +6,7 @@
   "dependencies": {},
   "devDependencies": {
     "cspell": "^2.1.12",
-    "markdownlint-cli": "^0.11.0"
+    "markdownlint-cli": "^0.12.0"
   },
   "scripts": {
     "cspell": "./cspell.sh",