Put dynamic field under project instead of project.optional-dependenc…

…ies (#1963)

The `dynamic = ["version"]` line should go under `[project]` instead of `[project.optional-dependencies]` when the `--mixed` flag is used.

src/templates/pyproject.toml.j2

@@ -13,13 +13,13 @@ classifiers = [
 {% if bindings == "cffi" -%}
 dependencies = ["cffi"]
 {% endif -%}
+dynamic = ["version"]
 {% if mixed_non_src -%}
 [project.optional-dependencies]
 tests = [
     "pytest",
 ]
 {% endif -%}
-dynamic = ["version"]
 
 {% if bindings in ["bin", "cffi", "pyo3", "rust-cpython"] or mixed_non_src -%}
 [tool.maturin]