time: exclude certain use statements and impl block on wasm32

otherwise the compiler will complain that they aren't used when
compiling the code for wasm32.

Signed-off-by: Shannon Sterz <s.sterz@proxmox.com>

proxmox-time/src/calendar_event.rs

@@ -1,3 +1,4 @@
+#[cfg(not(target_arch = "wasm32"))]
 use std::convert::TryInto;
 
 use anyhow::Error;

proxmox-time/src/daily_duration.rs

@@ -1,4 +1,6 @@
 use std::cmp::{Ordering, PartialOrd};
+
+#[cfg(not(target_arch = "wasm32"))]
 use std::convert::{TryFrom, TryInto};
 
 use anyhow::Error;

proxmox-time/src/date_time_value.rs

@@ -5,6 +5,7 @@ pub(crate) enum DateTimeValue {
     Repeated(u32, u32, Option<u32>),
 }
 
+#[cfg(not(target_arch = "wasm32"))]
 impl DateTimeValue {
     // Test if the entry contains the value
     pub fn contains(&self, value: u32) -> bool {