aws codebuild throwing error- can't open file, No such file or directory

Question

generatedata.py

import pandas as pd
import numpy as np

#Generate sample data

data = {
    'Name': ['Alice','Bob','Charlie','David','Emma'],
    'Age': np.random.randint(20,40, size=5),
    'Salary': np.random.randint(30000,80000, size=5)
}

#Create a dataframe
df = pd.DataFrame(data)

#Perform some data manipulation
df['Bonus'] = df['Salary'] * 0.1

#Display the Dataframe
print("Original dataframe:")
print(df)

# Store the data in an excel file
excel_filename = 'sample_data.xlsx'
df.to_excel(excel_filename, index=False)

print(f"\n Data saved to '{excel_filename}' successfully")

buildspec.yml

version: 0.2

phases:
  install:
    runtime-versions:
      python: 3.11

  pre_build:
    commands:
      - echo "Installing dependencies"
      - pip install pandas numpy

  build:
    commands:
      - echo "Running the script"
      - data-analysis/generatedata.py
      - aws s3 cp sample_data.xlsx s3://upload-data-files-to-s3/

I am trying to build the file and upload the excel into s3 bucket but the build is failing and throwing error that unable to find the file- generate data. Where as the given repository name and source is correct.

unable to understand what to correct here