fix decompression failed when unzip PostgreSQL11 in PowerShell 5.1

[YauHsien]

File decompression failed in PowerShell 5.1.

Description

Change lib/core.ps1 L542 from
$s = $s -replace '(\\+)$', '$1$1'
to
$s = $s -replace '(\\+)$', '$1'

because in current case scoop install postgresql11,
lib/decompress.ps1#L9 give an argument $DestinationPath ends with "\"
and make it failed when decompressing the file with 7zip 22.0.

Motivation and Context

Relate to ScoopInstaller/Main#3816
Relate to #4647

How Has This Been Tested?

1. Take a view of blame https://github.com/YauHsien/Scoop/blame/8aee6f99803d0f0aeab252e1d9d4848777185c51/lib/core.ps1#L544
   that segment is recently put in codebase.
2. Workaround in two of my laptops.
3. Scoop Core CI Tests https://github.com/YauHsien/Scoop/actions/runs/3409371442

Checklist:

• I have read the Contributing Guide.
• I have ensured that I am targeting the develop branch.
• I have updated the documentation accordingly.
• I have updated the tests accordingly.
• I have added an entry in the CHANGELOG.

[niheaven]

The trimming slash has been fixed in #5195 and is not related to #4647. Please wait for next release of Scoop. Thanks for contribution, though.