debian: lead webhttrack browser dep with chromium, not firefox-esr

webhttrack's "firefox-esr | chromium | www-browser" made the httrack
source inherit firefox-esr's autoremoval clock: britney keys off the
first alternative of a disjunction, so every firefox-esr RC bug
(currently #1127569) dragged httrack toward removal even though
webhttrack stays installable via the other alternatives.

Lead with chromium instead. lintian requires a real package as the
first alternative (virtual-package-depends-without-real-package-depends),
so the virtual www-browser cannot go first; chromium is real, keeps the
dep lintian-clean, and makes britney track chromium rather than the
RC-bug-prone firefox-esr.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Signed-off-by: Xavier Roche <roche@httrack.com>

debian/control

@@ -30,7 +30,7 @@ Description: Copy websites to your computer (Offline browser)
 Package: webhttrack
 Architecture: any
 Multi-Arch: foreign
-Depends: ${misc:Depends}, ${shlibs:Depends}, webhttrack-common, sensible-utils, firefox-esr | chromium | www-browser
+Depends: ${misc:Depends}, ${shlibs:Depends}, webhttrack-common, sensible-utils, chromium | firefox-esr | www-browser
 Replaces: webhttrack-common (<< 3.43.9-2)
 Breaks: webhttrack-common (<< 3.43.9-2)
 Suggests: httrack, httrack-doc