CLSA-2026-1792568971 Fix CVE(s): CVE-2026-61915

SECURITY UPDATE: double free in CalDAV VPATCH BYPARAM handling - debian/patches/CVE-2026-61915-pre.patch: do not free the PATCH-ACTION parameter already freed by icalpropertyremoveparameterbyref - debian/patches/CVE-2026-61915.patch: free the BYPARAM selector once after the property loop in...