Fix build versioning

README.md

@@ -6,11 +6,14 @@ Uses a discretization with local gauge invariance.
 
 ## Requirements
 
-- C++ compiles
+- C++ compiler
 - C++ libraries: Eigen, CppAD
-- Meson (build requirement)
+- Python 3
 
 ## Compiling
 
-See https://mesonbuild.com/Quick-guide.html#compiling-a-meson-project
+Assuming prerequisites are installed:
 
+`python3 -m pip install --user .`
+
+See also https://mesonbuild.com/Quick-guide.html#compiling-a-meson-project

pyproject.toml

@@ -2,7 +2,7 @@
 build-backend = 'mesonpy'
 requires = [
   'meson-python',
-  'numpy >= 1.19.0',
+  'oldest-supported-numpy',
   'pybind11',
 ]