Log Message:
shells/elvish: update to 0.20.0

Elvish 0.20.0 has been released on 2024-02-11, 11 months after 0.19.1, bringing
new features and bugfixes.

As usual, prebuilt binaries are offered for most common platforms.

Notable new features
 - A new os: module providing access to operating system functionality.
 - A new read-bytes command for reading a fixed number of bytes.
 - New commands in the file: module: file:open-output, file:seek and file:tell.
 - Maps now have their keys sorted when printed.
 - The peach command now has a &num-workers option (#648).
 - The from-json command now supports integers of arbitrary precision, and
   outputs them as exact integers rather than inexact floats.
 - A new str:fields command (#1689).
 - The order and compare commands now support a &total option, which allows
   sorting and comparing values of mixed types.
 - The language server now supports showing the documentation of builtin
   functions and variables on hover (#1684).
 - Elvish now respects the NO_COLOR environment variable. Builtin UI elements
   as well as styled texts will not have colors if it is set and non-empty.

Notable bugfixes
 - has-value $li $v now works correctly when $li is a list and $v is a composite
   value, like a map or a list.
 - A bug with how the hash code of a map was computed could lead to unexpected
   results when using maps as map keys; it has now been fixed.

Breaking changes
 - The except keyword in the try command was deprecated since 0.18.0 and is now
   removed. Use catch instead.
 - The float64 command was deprecated since 0.16.0 and emitted deprecation
   warnings since 0.19.1, and is now removed. Use num or inexact-num instead.

Deprecated features
Deprecated features will be removed in 0.21.0.
The following deprecated features trigger a warning whenever the code is parsed
and compiled, even if it is not executed:
 - The eawk command is now deprecated. Use re:awk instead.