refactor(lint): use clippy::or_fun_call (ratatui#1138)

<https://rust-lang.github.io/rust-clippy/master/index.html#or_fun_call>

Cargo.toml

@@ -90,6 +90,7 @@ mixed_read_write_in_expression = "warn"
 mod_module_files = "warn"
 needless_pass_by_ref_mut = "warn"
 needless_raw_strings = "warn"
+or_fun_call = "warn"
 redundant_type_annotations = "warn"
 rest_pat_in_fully_bound_structs = "warn"
 string_lit_chars_any = "warn"

src/widgets/calendar.rs

@@ -203,7 +203,7 @@ impl CalendarEventStore {
         let mut res = Self::default();
         res.add(
             OffsetDateTime::now_local()
-                .unwrap_or(OffsetDateTime::now_utc())
+                .unwrap_or_else(|_| OffsetDateTime::now_utc())
                 .date(),
             style.into(),
         );