change dependency versioning in Cargo.toml files in all example/ directories to no longer need local Embassy paths

[evanburger]

Problem: When building one of the example binaries (for example examples/rp/src/bin/wifi_blinky.rs), the Cargo.toml lists the Embassy dependencies as being local filesystem paths rather than remotely installed packages. When trying to remove the path assignment for those listed packages, the build breaks in a way that can't be easily resolved. It appears that the local Embassy repo pulled in from Github has different versions than what's on Crates.io.

Suggestion: Update the Cargo.toml files in the examples/ directories to use dependency versions that are building from just Crates.io and remove the need to use local Embassy packages. This would simplify using Embassy as a framework by just installing packages from Crates.io instead of needing to rely on the Github repository.

[Dirbaio]

The examples in latest git main use the crates from latest git main. To get examples which work with a given crates.io release you can check the repo at the corresponding tag. For example here for embassy-nrf v0.2.0 https://github.com/embassy-rs/embassy/tree/embassy-nrf-v0.2.0/examples/nrf52840