Fix haml-lint MultilineScript offense

A false positive is triggered by the linter MultilineScript, so this
explains the switch from =~ to match?.

On top of this, since Ruby 2.4, `String#match?`, `Regexp#match?` and
`Symbol#match?` have been added.  The methods are faster than
`match`/`=~`.  Because the methods avoid creating a `MatchData` object
or saving backref. So, when `MatchData` is not used, use `match?`
instead of `match`/`=~`.

src/api/.haml-lint_todo.yml

@@ -41,11 +41,6 @@ linters:
       - "app/views/webui/user/show.html.haml"
       - "app/views/webui/cloud/azure/configurations/show.html.haml"
 
-  # Offense count: 1
-  MultilineScript:
-    exclude:
-      - "app/views/webui/package/_rpmlint_log.html.haml"
-
   # Offense count: 6
   MultilinePipe:
     exclude:

src/api/app/views/webui/package/_rpmlint_log.html.haml

@@ -1,7 +1,7 @@
 - @log.lines.each do |line|
-  - if line =~ /\w+(?:\.\w+)+: W: /
+  - if line.match?(/\w+(?:\.\w+)+: W: /)
     = content_tag(:span, line.strip, style: 'color: olive;')
-  - elsif line =~ /\w+(?:\.\w+)+: E: /
+  - elsif line.match?(/\w+(?:\.\w+)+: E: /)
     = content_tag(:span, line.strip, style: 'color: red;')
   - else
     = line.strip