bug: Deprecated Call 'let-env' in asdf.nu

[heiytor]

Describe the Bug

It appears that the let-env call, which is currently used on asdf.nu and in the script to configure the config.nu, has been deprecated. As a result, an error message is displayed when using ASDF. To address this issue, I will open a pull request to resolve the deprecation of the let-env call and ensure that ASDF continues to function properly.

Steps to Reproduce

Follow the instructions in the Nushell & Git documentation.

Expected Behaviour

ASDF should work correctly, without any error messages:

Actual Behaviour

The following error message is shown: let-env' is deprecated

Environment

OS:
Linux windows 5.15.90.3-microsoft-standard-WSL2 #1 SMP Wed Jul 12 00:26:42 UTC 2023 x86_64 x86_64 x86_64 GNU/Linux

SHELL:
0.83.1

BASH VERSION:
5.1.16(1)-release

ASDF VERSION:
v0.12.0-624604a

ASDF INTERNAL VARIABLES:
ASDF_DEFAULT_TOOL_VERSIONS_FILENAME=.tool-versions
ASDF_DATA_DIR=/home/heiytor/.asdf
ASDF_DIR=/home/heiytor/.asdf
ASDF_CONFIG_FILE=/home/heiytor/.asdfrc

ASDF INSTALLED PLUGINS:
nodejs                       https://github.com/asdf-vm/asdf-nodejs.git master 4f8aa3d
python                       https://github.com/danhper/asdf-python.git master 8505457
rust                         https://github.com/code-lever/asdf-rust.git master 95acf4f

asdf plugins affected (if relevant)

No response