avoid chrono dependency, depend on proxmox 0.3.8

- remove chrono dependency

- depend on proxmox 0.3.8

- remove epoch_now, epoch_now_u64 and epoch_now_f64

- remove tm_editor (moved to proxmox crate)

- use new helpers from proxmox 0.3.8
  * epoch_i64 and epoch_f64
  * parse_rfc3339
  * epoch_to_rfc3339_utc
  * strftime_local

- BackupDir changes:
  * store epoch and rfc3339 string instead of DateTime
  * backup_time_to_string now return a Result
  * remove unnecessary TryFrom<(BackupGroup, i64)> for BackupDir

- DynamicIndexHeader: change ctime to i64

- FixedIndexHeader: change ctime to i64

src/bin/proxmox_backup_client/key.rs

@@ -1,7 +1,6 @@
 use std::path::PathBuf;
 
 use anyhow::{bail, format_err, Error};
-use chrono::Local;
 use serde::{Deserialize, Serialize};
 
 use proxmox::api::api;
@@ -112,7 +111,7 @@ fn create(kdf: Option<Kdf>, path: Option<String>) -> Result<(), Error> {
 
     match kdf {
         Kdf::None => {
-            let created = Local::now();
+            let created = proxmox::tools::time::epoch_i64();
 
             store_key_config(
                 &path,
@@ -180,7 +179,7 @@ fn change_passphrase(kdf: Option<Kdf>, path: Option<String>) -> Result<(), Error
 
     match kdf {
         Kdf::None => {
-            let modified = Local::now();
+            let modified = proxmox::tools::time::epoch_i64();
 
             store_key_config(
                 &path,