Bump version is failed if module has no serialized json file.

[dingmeng-xue]

serializedCmdletFile is null if module has no serialized json file for instance new module or preview module due to some reason.

Below code tries to generate cmdlet json file

azure-powershell/tools/VersionController/Models/VersionMetadataHelper.cs

Line 273 in 388e6a3

if (serializedCmdletFile == null)

But serializedCmdletFile should be fetched again. Otherwise, it throws exception and stop bumpversion pipeline.

azure-powershell/tools/VersionController/Models/VersionMetadataHelper.cs

Line 282 in 388e6a3

var oldModuleMetadata = DeserializeCmdlets(serializedCmdletFile);