Use abi3-py37 Python ABI, avoids excessive binaries

Thanks @ctrueden for the suggestion to use abi3. At
one point I read its more performant to build binaries
targeting specific Python interpreter versions but
I think thats for some other complex types (I also
can't seem to find that text anymore). Here with cellcast
and imgal we only pass primitives and arrays.

Author: elevans

Cargo.lock

@@ -15,5 +15,5 @@ doc = false
 [dependencies]
 cellcast = { path = "../cellcast" }
 imgal = "0.2.0"
-pyo3 = { version = "0.27.2", features = ["extension-module"]}
+pyo3 = { version = "0.27.2", features = ["extension-module", "abi3-py37"] }
 numpy = "0.27.1"

cellcast_python/Cargo.toml

@@ -19,17 +19,20 @@ classifiers = [
     "Operating System :: Unix",
     "Operating System :: MacOS",
     "Programming Language :: Python :: 3",
+    "Programming Language :: Python :: 3.7",
+    "Programming Language :: Python :: 3.8",
     "Programming Language :: Python :: 3.9",
     "Programming Language :: Python :: 3.10",
     "Programming Language :: Python :: 3.11",
     "Programming Language :: Python :: 3.12",
     "Programming Language :: Python :: 3.13",
+    "Programming Language :: Python :: 3.14",
     "Programming Language :: Rust",
     "Topic :: Scientific/Engineering",
     "Topic :: Scientific/Engineering :: Image Processing",
 ]
 
-requires-python = ">=3.9"
+requires-python = ">=3.7"
 dependencies = [
     "numpy",
 ]