Fix File path by removing the dot

[samer-shah]

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The issue

Running "pipenv shell" on MacOS in Powershell (pwsh) references incorrect Activate.ps1

issue link: #6318

The fix

Fix file path by removing the dot in shells.py

The checklist

• Associated issue (Running "pipenv shell" on MacOS in Powershell (pwsh) references incorrect Activate.ps1 #6318 )

• A news fragment in the news/ directory to describe this fix with the extension .bugfix.rst, .feature.rst, .behavior.rst, .doc.rst. .vendor.rst. or .trivial.rst (this will appear in the release changelog). Use semantic line breaks and name the file after the issue number or the PR #.