Make sure collections have trailing slashes (py-caldav is very pedantic about that)

crates/caldav/src/principal/mod.rs

@@ -48,7 +48,7 @@ impl Resource for PrincipalResource {
                 .map(|principal| puri.principal_uri(principal))
                 .flat_map(|principal_url| {
                     self.home_set.iter().map(move |&home_name| {
-                        HrefElement::new(format!("{}/{}", &principal_url, home_name))
+                        HrefElement::new(format!("{}{}/", &principal_url, home_name))
                     })
                 })
                 .collect(),

crates/caldav/src/principal/service.rs

@@ -46,6 +46,7 @@ impl<AP: AuthenticationProvider, S: SubscriptionStore, CS: CalendarStore, BS: Ca
     type PrincipalUri = CalDavPrincipalUri;
 
     const DAV_HEADER: &str = "1, 3, access-control, calendar-access";
+    const IS_COLLECTION: bool = true;
 
     async fn get_resource(
         &self,