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/benchmark.rs

@@ -3,7 +3,6 @@ use std::sync::Arc;
 
 use anyhow::{Error};
 use serde_json::Value;
-use chrono::Utc;
 use serde::Serialize;
 
 use proxmox::api::{ApiMethod, RpcEnvironment};
@@ -212,7 +211,7 @@ async fn test_upload_speed(
     verbose: bool,
 ) -> Result<(), Error> {
 
-    let backup_time = Utc::now();
+    let backup_time = proxmox::tools::time::epoch_i64();
 
     let client = connect(repo.host(), repo.user())?;
     record_repository(&repo);