Update dependency slack-messenger to v2.3.5

This MR contains the following updates:

Package	Update	Change
slack-messenger	patch	2.3.4 -> 2.3.5

MR created with the help of gitlab-org/frontend/renovate-gitlab-bot

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Release Notes

gitlab-org/slack-notifier (slack-messenger)

v2.3.5

• use RE2 and UntrustedRegexp to avoid potential abuse with Ruby Regexp and gsub

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