Remove 0.0 when there is no trade, sams as monthly_heatmap_detailedview

[twkim112]

Changes:

• Removed 0.0 when there is no trade in the monthly_heatmap function.
• Added a mask to filter out 0.0 values.
• Removed grid

These changes align the behavior of the monthly_heatmap function with the monthly_heatmap_detailedview function.

Here is sample figure with BTC's close data.

[korbit-ai]

My review is in progress 📖 - I will have feedback for you in a few minutes!

[korbit-ai]

The code uses bare except clauses in a couple of places to catch all exceptions without specifying the exception type. This can make it difficult to identify and handle specific types of exceptions. Consider replacing the bare except clauses with specific exception types that you expect and want to handle, such as ValueError, KeyError, etc. This will make the exception handling more explicit and allow you to handle different exceptions appropriately.