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

examples/download-speed.rs

@@ -2,8 +2,6 @@ use std::io::Write;
 
 use anyhow::{Error};
 
-use chrono::{DateTime, Utc};
-
 use proxmox_backup::api2::types::Userid;
 use proxmox_backup::client::{HttpClient, HttpClientOptions, BackupReader};
 
@@ -36,7 +34,7 @@ async fn run() -> Result<(), Error> {
 
     let client = HttpClient::new(host, username, options)?;
 
-    let backup_time = "2019-06-28T10:49:48Z".parse::<DateTime<Utc>>()?;
+    let backup_time = proxmox::tools::time::parse_rfc3339("2019-06-28T10:49:48Z")?;
 
     let client = BackupReader::start(client, None, "store2", "host", "elsa", backup_time, true)
         .await?;

examples/upload-speed.rs

@@ -16,7 +16,7 @@ async fn upload_speed() -> Result<f64, Error> {
 
     let client = HttpClient::new(host, username, options)?;
 
-    let backup_time = chrono::Utc::now();
+    let backup_time = proxmox::tools::time::epoch_i64();
 
     let client = BackupWriter::start(client, None, datastore, "host", "speedtest", backup_time, false, true).await?;