commitlint.sh: simplify

Rather use more straightforward package names, as advised
in [1] and [2].

[1] conventional-changelog/commitlint#3892
[2] Kochava/github-workflows#30

Author: knocte

commitlint.sh

@@ -4,7 +4,7 @@ set -euxo pipefail
 # cd to directory of this script
 cd "$(dirname "$0")"
 npm install
-npm install conventional-changelog-conventionalcommits commitlint@latest
-./node_modules/commitlint/cli.js --version
-./node_modules/commitlint/cli.js $@
+npm install @commitlint/config-conventional @commitlint/cli
+./node_modules/@commitlint/cli/cli.js --version
+./node_modules/@commitlint/cli/cli.js $@
 cd ..