Remove examples from the Cargo.toml workspace to prevent compiler warning

[Sycrosity]

Currently, when compiling picoserve, all of the workspace members are included in the crate, leading to these being downloaded although they are never used. Removing the examples from the Cargo.toml members list, as is done in esp_hal and embassy (who don't even have a root Cargo.toml)

warning: skipping duplicate package `web_sockets` found at `/Users/[me]/.cargo/git/checkouts/picoserve-521def08cc55ec79/1f429b6/examples/embassy/web_sockets`
warning: skipping duplicate package `hello_world` found at `/Users/[me]/.cargo/git/checkouts/picoserve-521def08cc55ec79/1f429b6/examples/embassy/hello_world`

[Sycrosity]

(although this is super unimportant)