gcovr: new port

[szhorvat]

Description

Type(s)

• bugfix
• enhancement
• security fix

Tested on

macOS 14.7.2 23H311 arm64
Xcode 16.2 16C5032a

Verification

Have you

• followed our Commit Message Guidelines?
• squashed and minimized your commits?
• checked that there aren't other open pull requests for the same change?
• referenced existing tickets on Trac with full URL in commit message?
• checked your Portfile with port lint?
• tried existing tests with sudo port test?
• tried a full install with sudo port -vst install?
• tested basic functionality of all binary files?
• checked that the Portfile's most important variants haven't been broken?

[szhorvat]

What is the preferred default Python version for new ports? I chose 3.12 because the boost port (which many other ports depend on) uses it, therefore this version is likely already installed for most people.

[szhorvat]

Bumped Python version to 3.13.