Fix serial port URI parsing in board attach command

[rsora]

Please check if the PR fulfills these requirements

• The PR has no duplicates (please search among the Pull Requests before creating one)
• The PR follows our contributing guidelines
• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)

• What kind of change does this PR introduce?

Fixes bug on windows related to board attach command

• What is the current behavior?

The message

Attach board error: no supported board found at serial://COM7

is returned even if a board is attached to COM7 port

C:\Users\umber\Downloads\empty>..\arduino-cli.exe board list
Port Type              Board Name            FQBN                     Core         
COM3 Serial Port       Unknown
COM4 Serial Port       Unknown
COM7 Serial Port (USB) Arduino MKR WiFi 1010 arduino:samd:mkrwifi1010 arduino:samd

• What is the new behavior?

• Does this PR introduce a breaking change?

• Other information:

There is already an integration test that uses board attach command

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