Fixed broken CI dependency (TracSpamFilter)

Author: bmispelon

requirements.txt

@@ -6,7 +6,7 @@ Django==4.2.14
 libsass==0.23.0
 
 # Trac plugins
-TracSpamFilter[dns,spambayes] @ https://trac.edgewall.org/browser/plugins/trunk/spam-filter?rev=17766&format=zip
+TracSpamFilter[dns,spambayes] @ svn+https://svn.edgewall.org/repos/trac/plugins/trunk/spam-filter@17838
 TracDragDrop @ svn+https://trac-hacks.org/svn/tracdragdropplugin/0.12@18635
 
 # No pypi release compatible with trac 1.6 yet