Remove redundant primitive-key constraint for old Mono compatibility - #63

Node.js 20 is deprecated. The following actions target Node.js 20 but are being forced to run on Node.js 24: actions/checkout@v4.2.2, actions/setup-dotnet@v4.1.0, actions/upload-artifact@v4.5.0. For more information see: https://github.blog/changelog/2025-09-19-deprecation-of-node-20-on-github-actions-runners/

The type 'TKey' cannot be used as type parameter 'TKey' in the generic type or method 'Dictionary<TKey, TValue>'. Nullability of type argument 'TKey' doesn't match 'notnull' constraint.

The type 'TKey' cannot be used as type parameter 'TKey' in the generic type or method 'Enumerable.ToDictionary<TSource, TKey, TElement>(IEnumerable<TSource>, Func<TSource, TKey>, Func<TSource, TElement>)'. Nullability of type argument 'TKey' doesn't match 'notnull' constraint.

The type 'TKey' cannot be used as type parameter 'TKey' in the generic type or method 'Dictionary<TKey, TValue>'. Nullability of type argument 'TKey' doesn't match 'notnull' constraint.

The type 'TKey' cannot be used as type parameter 'TKey' in the generic type or method 'Dictionary<TKey, TValue>'. Nullability of type argument 'TKey' doesn't match 'notnull' constraint.

The type 'TKey' cannot be used as type parameter 'TKey' in the generic type or method 'Enumerable.ToDictionary<TSource, TKey, TElement>(IEnumerable<TSource>, Func<TSource, TKey>, Func<TSource, TElement>)'. Nullability of type argument 'TKey' doesn't match 'notnull' constraint.

The type 'TKey' cannot be used as type parameter 'TKey' in the generic type or method 'Dictionary<TKey, TValue>'. Nullability of type argument 'TKey' doesn't match 'notnull' constraint.

The type 'TKey' cannot be used as type parameter 'TKey' in the generic type or method 'Dictionary<TKey, TValue>'. Nullability of type argument 'TKey' doesn't match 'notnull' constraint.

The type 'TKey' cannot be used as type parameter 'TKey' in the generic type or method 'Enumerable.ToDictionary<TSource, TKey, TElement>(IEnumerable<TSource>, Func<TSource, TKey>, Func<TSource, TElement>)'. Nullability of type argument 'TKey' doesn't match 'notnull' constraint.

The type 'TKey' cannot be used as type parameter 'TKey' in the generic type or method 'Dictionary<TKey, TValue>'. Nullability of type argument 'TKey' doesn't match 'notnull' constraint.