Update async_executors requirement from 0.2 to 0.4 in /language-server

[dependabot-preview]

Updates the requirements on async_executors to permit the latest version.

Changelog

Sourced from async_executors's changelog.

0.4.0

• add support for async-global-executor v2.
• add support for tokio v1

0.4.0-beta.2 - 2020-11-05

• add support for async-global-executor.

0.4.0-beta.1 - 2020-11-01

• BREAKING CHANGE: support tokio 0.3. Will go out of beta when tokio releases 1.0.
• add example for use with tracing.
• update cargo deny.

0.3.0 - 2020-06-10

• update to async-std 1.6. Local spawn still requires the unstable feature on async-std so async_executors enables that.

0.3.0-beta.1 - 2020-05-10

• futures 0.3.5 has been released, so we no longer have to vendor RemoteHandle. It means we are now forbid( unsafe ) and the spawn_handle feature has been removed since we no longer require extra dependencies in order to provide the traits.
• update to async-std 1.6.0-beta.1. Async-std is now backed by smol. It now supports Wasm and LocalSpawn. Local spawning is unstable, so we turn on the unstable feature. As they are still in beta, we reflect that in our version.

0.2.2 - 2020-04-25

• Temporarily remove forbid unsafe. A non-breaking change update of pin-utils now causes a macro to no longer pass. We have this because we vendor RemoteHandle from futures until they release a new version.
• Improve an error message for a panic on JoinHandle.

0.2.1 - 2020-04-08

• FIX: JoinHandle::detach didn't work properly. Sorry, my bad as it wasn't even tested.
• remove the Unpin impl from JoinHandle. The joinhandle is still Unpin anyway.
• run cargo deny in CI.
• Vamp up the docs, removing some errors and adding examples.
• TokioCt and TokioTp block_on no longer require &mut self, just &self. Since they implement Clone, it didn't protect against re-entrance anyway.
• improve performance of spawn_handle_local on TokioCt as I mistakenly thought tokio::JoinHandle<T> required T to be Send, so I was not using the native JoinHandle.
• only build on default target on docs.rs.
• clean up and configure the CI configuration.

0.2 - 2020-02-29

• tracing-futures 0.2.3 is out, so no patching required anymore.

Commits

• 1b164cf Merge branch 'dev'
• d3b3592 Add tests for async-global-executor on Wasm.
• f872653 Prep release 0.4
• 801c9af Merge branch 'dev' into master
• 1ebede0 bump version and changelog.
• 2554a89 Add support for async-global-executor
• 82c5818 Add missing test to async_std.
• f8b3681 Merge branch 'dev' into master
• a2bf103 add smolscale to todo
• 789d0f0 bump version numbers and prep release.
• Additional commits viewable in compare view

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[codecov]

Codecov Report

Merging #30 (214228a) into master (6e70215) will decrease coverage by 0.18%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master      #30      +/-   ##
==========================================
- Coverage   60.81%   60.62%   -0.19%     
==========================================
  Files          12       12              
  Lines         541      541              
==========================================
- Hits          329      328       -1     
- Misses        212      213       +1     

Impacted Files	Coverage Δ
language-server/src/lib.rs	82.45% <0.00%> (-8.78%)	⬇️
language-server-macros/src/client.rs	0.00% <0.00%> (ø)
language-server-macros/src/server.rs	0.00% <0.00%> (ø)
language-server/tests/integration.rs	100.00% <0.00%> (ø)
language-server/src/client.rs	86.51% <0.00%> (+0.47%)	⬆️

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