Update opendal to 0.40.0

Allows to remove the direct dependency on backon

Cargo.lock

@@ -2315,7 +2315,6 @@ dependencies = [
  "ar",
  "assert_cmd",
  "async-trait",
- "backon",
  "base64 0.21.0",
  "bincode",
  "blake3",

Cargo.toml

@@ -27,7 +27,6 @@ strip = true
 anyhow = { version = "1.0", features = ["backtrace"] }
 ar = "0.9"
 async-trait = "0.1"
-backon = "0.4.1"
 base64 = "0.21"
 bincode = "1"
 blake3 = "1"