Upgrade to latest Leptos@0.4.1 and others

[sectore]

and others (strum, tower-http).

Notes about upgrading Leptos:

• Release notes + changes https://github.com/leptos-rs/leptos/releases/tag/v0.4.0
• leptos::ServerFn::register is deprecated now

  warning: use of deprecated associated function `leptos::ServerFn::register`: Explicit server function registration is no    longer required on most platforms (including Linux, macOS, iOS, FreeBSD, Android, and Windows). If you are on another    platform and need to explicitly register server functions, call ServerFn::register_explicit() instead.

Closes #182 Closes #181 Closes #178 Close #177

[FelixWeis]

Thanks for keeping this up to date!