Wasm compatibility

[Dicklessgreat]

This pull request introduces compatibility with the wasm32-unknown-unknown target and replaces the standard library's time utilities with the web_time crate to improve cross-platform support. The changes also include updates to dependencies and documentation to reflect these enhancements.

Motivation

I am using dioxus and reqwest to send requests from the frontend to the backend. To enhance the client functionality, I needed to use reqwest-middleware and reqwest-retry. However, when trying this in a WASM environment, I encountered a runtime panic. Message below is from the browser’s developer tools:

panicked at library/std/src/sys/pal/wasm/../unsupported/time.rs:31:9:
time not implemented on this platform

This panic occurs because this crates use std::time::{Duration, SystemTime}, which are not supported in wasm32-unknown-unknown.

To resolve this, I replaced those with the web_time crate.

Compatibility with wasm32-unknown-unknown target:

• .cargo/config.toml: Added rustflags configuration for the wasm32-unknown-unknown target to specify the getrandom_backend="wasm_js" feature. Please refer getrandom doc to see why this config is necessary(for checking if this crate is buildable on wasm32-unknown-unknown by cargo build --features=wasm --target=wasm32-unknown-unknown)
• Cargo.toml: Added new dependencies (web-time, getrandom) and defined a wasm feature for compatibility with the wasm32-unknown-unknown target.

Transition to web_time crate:

• src/policies/exponential_backoff.rs: Replaced std::time::{Duration, SystemTime} with web_time::{Duration, SystemTime} across the file, including examples and implementations. [1] [2] [3] [4] [5]
• src/retry_policy.rs: Updated imports to use web_time::{Duration, SystemTime} instead of the standard library equivalents. [1] [2]

Documentation updates:

• CHANGELOG.md: Added a note about compatibility with wasm32-unknown-unknown in the changelog under the "Added" section.

[Dicklessgreat]

Hi! Just checking in on this PR.
It's been a while, so I wanted to ask if there's anything I can do to help move it forward.
Happy to adjust the implementation if needed.
Thanks!