Fix(strip_html): handle multiline comments

The `strip_html` filter was not correctly handling multiline HTML
comments. This was due to the regex using the `m` flag instead of the `s`
flag. The `m` flag only makes `^` and `$` match the start and end of
lines, while the `s` flag makes `.` match any character, including
newlines.

This commit changes the regex flags from `m` to `s` for both
`@html_blocks` and `@html_tags` to correctly handle multiline content.

A doctest has been added to cover the failing case.

Author: google-labs-jules[bot]

.tool-versions

@@ -1,2 +1,3 @@
 erlang 27.0
 elixir 1.17.2
+ruby 3.3.0

lib/solid/standard_filter.ex

@@ -1137,9 +1137,11 @@ defmodule Solid.StandardFilter do
   Output
   iex> Solid.StandardFilter.strip_html("Have <em>you</em> read <strong>Ulysses</strong>?")
   "Have you read Ulysses?"
+  iex> Solid.StandardFilter.strip_html("<!-- foo bar \\n test -->test")
+  "test"
   """
-  @html_blocks ~r{(<script.*?</script>)|(<!--.*?-->)|(<style.*?</style>)}m
-  @html_tags ~r|<.*?>|m
+  @html_blocks ~r{(<script.*?</script>)|(<!--.*?-->)|(<style.*?</style>)}s
+  @html_tags ~r|<.*?>|s
   @spec strip_html(iodata()) :: String.t()
   def strip_html(iodata) do
     iodata

test/solid/integration/scenarios/filter/input.liquid

@@ -587,3 +587,7 @@ sort_natural
 {{ (0..15) | sort_natural | join: ", " }}
 {{ 123 | sort_natural | join: ", " }}
 {{ fruits | sort_natural | join: ", " }}
+
+strip_html
+
+{{ "<!-- foo bar \\n test -->test" | strip_html }}