Pin a known-working version of radicale too

Author: Hugo Osvaldo Barrera

tests/storage/servers/radicale/install.sh

@@ -2,7 +2,7 @@
 set -e
 
 if [ "$REQUIREMENTS" = "release" ] || [ "$REQUIREMENTS" = "minimal" ]; then
-    radicale_pkg="radicale"
+    radicale_pkg="radicale==2.1.10"
 elif [ "$REQUIREMENTS" = "devel" ]; then
     radicale_pkg="git+https://github.com/Kozea/Radicale.git"
 else