cargo: bump async-trait from 0.1.48 to 0.1.50

Bumps [async-trait](https://github.com/dtolnay/async-trait) from 0.1.48 to 0.1.50.
- [Release notes](https://github.com/dtolnay/async-trait/releases)
- [Commits](https://github.com/dtolnay/async-trait/compare/0.1.48...0.1.50)

Signed-off-by: dependabot[bot] <support@github.com>

Cargo.lock

@@ -405,9 +405,9 @@ checksum = "e91831deabf0d6d7ec49552e489aed63b7456a7a3c46cff62adad428110b0af0"
 
 [[package]]
 name = "async-trait"
-version = "0.1.48"
+version = "0.1.50"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "36ea56748e10732c49404c153638a15ec3d6211ec5ff35d9bb20e13b93576adf"
+checksum = "0b98e84bbb4cbcdd97da190ba0c58a1bb0de2c1fdf67d159e192ed766aeca722"
 dependencies = [
  "proc-macro2",
  "quote",

Cargo.toml

@@ -22,7 +22,7 @@ async-smtp = { git = "https://github.com/async-email/async-smtp", rev="2275fd8d1
 async-std-resolver = "0.19.5"
 async-std = { version = "~1.8.0", features = ["unstable"] }
 async-tar = "0.3.0"
-async-trait = "0.1.31"
+async-trait = "0.1.50"
 backtrace = "0.3.33"
 base64 = "0.13"
 bitflags = "1.1.0"