Update Rust crate lettre to 0.10.0-rc.3

Author: renovate-bot

Cargo.toml

@@ -63,7 +63,7 @@ http = "0.2"
 hyper = { version = "0.14", features = ["client", "http1"] }
 indexmap = { version = "1.7.0", features = ["serde-1"] }
 jemallocator = { version = "0.3", features = ['unprefixed_malloc_on_supported_platforms', 'profiling'] }
-lettre = { version = "0.10.0-beta.3", default-features = false, features = ["file-transport", "smtp-transport", "native-tls", "hostname", "builder"] }
+lettre = { version = "0.10.0-rc.3", default-features = false, features = ["file-transport", "smtp-transport", "native-tls", "hostname", "builder"] }
 license-exprs = "1.6"
 minijinja = "0.6.0"
 oauth2 = { version = "4.0.0", default-features = false, features = ["reqwest"] }