Update tokio requirement from 0.1.18 to 0.2.10

[dependabot-preview]

Updates the requirements on tokio to permit the latest version.

Release notes

Sourced from tokio's releases.

Tokio v0.2.10

Introduces a task-local storage solution that works with Rust's "task" concept and supports multiplexing futures on the same runtime task (#2126). A number of other incremental improvements are included.

This release includes a few fixes, including fixing a scenario in which undefined behavior could be introduced when the user provided a buggy AsyncRead implementation.

Fixes

• #[tokio::main] when rt-core feature flag is not enabled (#2139).
• remove AsyncBufRead from BufStream impl block (#2108).
• potential undefined behavior when implementing AsyncRead incorrectly (#2030).

Added

• BufStream::with_capacity (#2125).
• impl From and Default for RwLock (#2089).
• io::ReadHalf::is_pair_of checks if provided WriteHalf is for the same underlying object (#1762, #2144).
• runtime::Handle::try_current() returns a handle to the current runtime (#2118).
• stream::empty() returns an immediately ready empty stream (#2092).
• stream::once(val) returns a stream that yields a single value: val (#2094).
• stream::pending() returns a stream that never becomes ready (#2092).
• StreamExt::chain() sequences a second stream after the first completes (#2093).
• StreamExt::collect() transform a stream into a collection (#2109).
• StreamExt::fuse ends the stream after the first None (#2085).
• StreamExt::merge combines two streams, yielding values as they become ready (#2091).
• Task-local storage (#2126).

Commits

• bffbaab chore: prepare v0.2.10 release (#2148)
• a5e774b sync: derive PartialEq for error enums (#2137)
• 0bb1730 sync: add std error impl for broadcast errors (#2141)
• c7719a2 io: simplify split check (#2144)
• 38bff0a macros: fix #[tokio::main] without rt-core (#2139)
• fbe143b fix: Prevent undefined behaviour from malicious AsyncRead impl (#2030)
• 9df805f chore: do not depend on loom on windows (#2146)
• 5d82ac2 readme: Add more related tokio projects (#2128)
• 5bf78d7 Add a method to test if split streams come from the same stream. (#1762)
• 3176d0a io: add BufStream::with_capacity (#2125)
• Additional commits viewable in compare view

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[dependabot-preview]

Superseded by #52.