Release 0.7.2

[shivamsn97]

Patch release. Two fixes land:

• Fresh installs work again — the scaffolded requirements.txt pinned starlette>=0.37,<0.38, which conflicts with the framework's own starlette>=1.3.1 requirement, so pip install -r requirements.txt in a brand-new project failed to resolve. The scaffold now pins starlette>=1.3.1,<2.0.
• pyxle serve --port rejects a boolean instead of silently binding port 1 (because bool is an int subclass in Python).

No API changes. Upgrade with pip install --upgrade pyxle-framework.