⬆️ Update alpine_3_21/nginx to v1.26.3-r0 (#268)

Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

Author: renovate[bot]

mailfilter/Dockerfile

@@ -18,7 +18,7 @@ ARG S6_OVERLAY_VERSION="v3.2.0.2"
 # Setup base
 
 RUN apk add --no-cache \
-    nginx=1.26.2-r4 \
+    nginx=1.26.3-r0 \
     freshclam=1.4.2-r0 \
     clamav-scanner=1.4.2-r0 \
     clamav-daemon=1.4.2-r0 \