fix: Update minimum Python version in pyproject.toml and CI workflow to ensure compatibility and streamline version management

.github/workflows/ci.yml

@@ -382,7 +382,7 @@ jobs:
       #   - Programming Language :: Python :: {{LATEST-2}} → 3.11
       #   - Programming Language :: Python :: {{LATEST-1}} → 3.12
       #   - Programming Language :: Python :: {{LATEST}} → 3.13
-      #   - requires-python = ">=3.{{LATEST-4}}" → ">=3.9"
+      #   - requires-python: Updates minimum version if it changes (currently >=3.9)
       # Preserves all other classifiers including Development Status :: 5 - Production/Stable
       run: |
         python << 'EOF'
@@ -395,6 +395,7 @@ jobs:
         python_versions = json.loads(python_versions_str)
         
         print(f"Updating pyproject.toml with Python versions: {python_versions}")
+        print(f"Minimum Python version: {python_versions[0]}")
         
         # Read pyproject.toml
         with open('pyproject.toml', 'r') as f:
@@ -410,15 +411,27 @@ jobs:
         
         print(f"Placeholder mappings: {replacements}")
         
+        # Get minimum version for requires-python
+        min_version = python_versions[0]
+        
         # Process each line and replace placeholders
         updated_lines = []
         for line in lines:
             updated_line = line
-            # Replace Python version placeholders
+            
+            # Replace Python version placeholders in classifiers
             for placeholder, version in replacements.items():
                 if placeholder in line:
                     updated_line = updated_line.replace(placeholder, version)
                     print(f"  Replaced: {placeholder} → {version}")
+            
+            # Update requires-python to use minimum version (if it's still at default)
+            if 'requires-python' in line and '>=3.9' in line:
+                # Only update if we're changing to a different minimum version
+                if min_version != '3.9':
+                    updated_line = line.replace('>=3.9', f'>={min_version}')
+                    print(f"  Updated requires-python: >=3.9 → >={min_version}")
+            
             updated_lines.append(updated_line)
         
         # Write back to pyproject.toml