Fix: Update pivot_table for pandas 2.0+ compatibility

[blu3-bird]

Problem

pivot_table() with aggfunc='sum' fails on pandas 2.0+ when DataFrame contains non-numeric columns.

Solution

Filter to numeric columns before applying pivot_table:

# Before
df_sales.pivot_table(index='Gender', aggfunc='sum').round(1)

# After
numeric_df = df_sales.select_dtypes(include='number')
numeric_df['Gender'] = df_sales['Gender']
numeric_df.pivot_table(index='Gender', aggfunc='sum').round(1)

Fix Issue #1