chore: bust stale Camo cache showing v0.1.0 PyPI badge (#4)

Same fix as SocialAPIsHub/socialapis-python: GitHub's Camo proxy
cached the SVG from before v0.1.1 published and won't revalidate
for hours. Swapping the badge URL to one Camo hasn't seen forces
a fresh fetch.

New URL also adds cacheSeconds=300 (so shields.io itself caches
for only 5 min going forward, limiting future drift) and the
PyPI logo for visual weight. Same target — clicking still routes
to pypi.org/project/socialapis-sdk.