Fix whitespace stripping in video warning template

Applied the same inline computation fix to {video_warning} placeholder
that was previously done for {common_date} and {common_location}.

Computes video_warning_text inline using {%- set -%} syntax instead of
storing as a separate HA variable, which strips leading whitespace.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

manifest.json

@@ -1,3 +1,3 @@
 {
-  "version": "1.22.7"
+  "version": "1.22.8"
 }