Use the "official" calendar URL for meetings

Fetch the iCalendar file from an URL and show the meetings that are
planned in the future.

Because almost everything was touched, this commit also incorporates a
cargo update.

Cargo.toml

@@ -4,5 +4,16 @@ version = "0.1.0"
 edition = "2021"
 
 [dependencies]
-time = { version = "0.3.36", features = ["macros", "formatting", "local-offset", "wasm-bindgen"] }
+anyhow = "1.0.98"
+chrono = "0.4.40"
+futures-util = "0.3.31"
+icalendar = { version = "0.16.1", features = ["chrono-tz"] }
+reqwest = "0.12.4"
+tracing = "0.1.41"
+tracing-subscriber = { version = "0.3.19", features = ["time"] }
+tracing-web = "0.1.3"
+wasm-bindgen = "0.2.100"
 yew = { version = "0.21.0", features = ["csr"] }
+
+[dev-dependencies]
+tokio = { version = "1.37.0", features = ["macros", "rt-multi-thread"] }