parse_savename does not properly identify the prefix when the first key=value pair's key contains "_"

[liuyxpp]

Describe the bug
A clear and concise description of what the bug is.

parse_savename can not correctly handle the case when the first key=value pair's key contains "_"

Minimal Working Example
Please provide a piece of code that leads to the bug you encounter.

julia> parse_savename("base_dir=._config=config_data_format=HDF5")
("base", Dict{String, Any}("config" => "config", "data_format" => "HDF5", "dir" => "."), "")

It is expected that "base" should not be prefix, but a part of the variable name base_dir.

If the code is runnable, it will help us identify the problem faster.

Please also provide the version of DrWatson you have installed and your Julia version.

DrWatson: v2.9.1
Julia: v1.7.2