Share a single MongoClient and fix LiteDB TableCollection - #757

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, actions/setup-dotnet@v4. For more information see: https://github.blog/changelog/2025-09-19-deprecation-of-node-20-on-github-actions-runners/

'DataTestMethod' is obsolete. Use 'TestMethod' instead. (https://learn.microsoft.com/dotnet/core/testing/mstest-analyzers/mstest0044)

'PowerExcelExtensions.Rows(ISheet)' is obsolete: 'This method is obsolete. Use the new method instead.'

'DataTestMethod' is obsolete. Use 'TestMethod' instead. (https://learn.microsoft.com/dotnet/core/testing/mstest-analyzers/mstest0044)

'PowerExcelExtensions.Rows(ISheet)' is obsolete: 'This method is obsolete. Use the new method instead.'

'DataTestMethod' is obsolete. Use 'TestMethod' instead. (https://learn.microsoft.com/dotnet/core/testing/mstest-analyzers/mstest0044)