[FLINK-37746] Added serialVersionUID in MapTypeInfo class

[pranav234]

What is the purpose of the change

Adding serialVersionUID in MapTypeInfo class

Verifying this change

This change is a trivial rework / code cleanup without any test coverage.

Does this pull request potentially affect one of the following parts:

• Dependencies (does it add or upgrade a dependency): No
• The public API, i.e., is any changed class annotated with @Public(Evolving): Yes
• The serializers: (yes / no / don't know) no
• The runtime per-record code paths (performance sensitive): no
• Anything that affects deployment or recovery: JobManager (and its components), Checkpointing, Kubernetes/Yarn, ZooKeeper: no
• The S3 file system connector: no

Documentation

• Does this pull request introduce a new feature? no
• If yes, how is the feature documented? Not applicable

[flinkbot]

CI report:

• 310ba7e6509accf815a84fc27e724d1cd3b90754 Azure: SUCCESS

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