Loosen versioneer version requirement from exact to min version

Makes downstream packaging simpler and more robust, avoiding the need
for downstream patches when versioneer is updated.

Building with versioneer v0.29.0 works fine on Arch Linux, see:

  https://aur.archlinux.org/packages/python-pytensor

pyproject.toml

@@ -3,7 +3,7 @@ requires = [
   "setuptools>=48.0.0",
   "cython",
   "numpy>=1.17.0",
-  "versioneer[toml]==0.28",
+  "versioneer[toml]>=0.28",
 ]
 build-backend = "setuptools.build_meta"