v1.2.0: Resolve Windows instability and allow wider numpy range

• Resolve Windows instability by reverting back to the v0.7 version of the vendored Blis library we'd been using. This was surprisingly hard to do, because I had a lot of trouble getting it to compile due to conflicts between cpuid.h and intrin.h on Windows.
• Widen the runtime numpy compatibility range to allow usage alongside numpy 1 and numpy 2. We still build against numpy 2 though.