commitlint.sh,CI: use a previous version to fix CI

The last version of commitlint is making our tests fail. My
suspicions for why are the following:

* After their massive refactoring migrating to ESM [1], they
somehow changed their sub-package @commitlint/types, which I
reported as bug 3942 [2].

* When fixing bug 3942 [3], they updated their dependency to
`@types/conventional-commits-parser` to a higher version (from
3.0.6 to 5.0.0). Version 5.0.0 of that package is about 18
days old, however, version 5.0.0 of package
`conventional-commits-parser` [4] is 6 months old! But the
worst is that the previous version 3.0.6 (which is the one
that commitlint was using before this update) was published
about 4 years ago! So I'm guessing our plugins were compatible
with very old versions of this internal component and now its
update has exposed bugs.

[1] conventional-changelog/commitlint@3423735
[2] conventional-changelog/commitlint#3942
[3] conventional-changelog/commitlint@5a01f59
[4] https://www.npmjs.com/package/conventional-commits-parser

.github/workflows/CI.yml

@@ -92,7 +92,7 @@ jobs:
           npm install --verboase --global yarn
           yarn add --dev jest typescript ts-jest @types/jest
       - name: Install commitlint dependencies
-        run: npm install --verbose @commitlint/types
+        run: npm install --verbose @commitlint/types@18.6.1
       - name: Print versions
         run: |
           git --version
@@ -122,7 +122,7 @@ jobs:
           npm install --verbose --global yarn
           yarn add --dev jest typescript ts-jest @types/jest ts-node
       - name: Install commitlint dependencies
-        run: npm install --verbose @commitlint/types
+        run: npm install --verbose @commitlint/types@18.6.1
       - name: Run typescript compiler
         run: npx tsc
       - name: Print versions

commitlint.sh

@@ -4,6 +4,6 @@ set -euxo pipefail
 # cd to directory of this script
 cd "$(dirname "$0")"
 npm install --verbose
-npm install --verbose @commitlint/config-conventional
+npm install --verbose @commitlint/config-conventional@18.6.1
 npx commitlint --version
 npx commitlint $@