i don't like it but maybe it will work

ci/recipe/meta.yaml

@@ -1,4 +1,4 @@
-{%- set pyproject_toml = load_file('..', 'pyproject.toml') | parse_toml %}
+{%- set pyproject_toml = load_data('parse_pyproject_toml.py') %}
 {%- set version = pyproject_toml.get('project', {}).get('version', 'placehold') %}
 
 package:
@@ -23,6 +23,7 @@ requirements:
     - pip
     - setuptools
     - wheel
+    - toml      # this is needed to ensure the toml module is available
 
   run:
     - python {{ python }}

ci/recipe/parse_pyproject_toml.py

@@ -0,0 +1,13 @@
+import toml
+import os
+
+
+def parse_toml(file_path):
+    with open(file_path, 'r') as f:
+        return toml.load(f)
+
+
+# This function will be called by conda-build to load the pyproject.toml data
+def main():
+    pyproject_toml_path = os.path.join(os.getcwd(), 'pyproject.toml')
+    return parse_toml(pyproject_toml_path)