BUG: when i merge two dataframes in pandas if the datatypes of columns are mismatched  exception is raised
- [ ] I have checked that this issue has not already been reported.

- [ ] I have confirmed this bug exists on the latest version of pandas.

- [ ] (optional) I have confirmed this bug exists on the master branch of pandas.

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**Note**: Please read [this guide](https://matthewrocklin.com/blog/work/2018/02/28/minimal-bug-reports) detailing how to provide the necessary information for us to reproduce your bug.

#### Code Sample, a copy-pastable example

```python
# Your code here
import pandas as pd
data_right = [['Alex','10',100],['Bob','12',90],['Clarke','13.0',80]]
data_left =[[10.0],[12.0],[13.0]]
df_right = pd.DataFrame(data_right,columns=['Name','Age','score'])
df_left  = pd.DataFrame(data_left,columns=['Age'])
df_result=df_left.merge(df_right,on='Age',how='inner')

print(df_result)
```

#### Problem description

[this should explain **why** the current behaviour is a problem and why the expected output is a better solution]

sometimes when I read from files in some storage .I am not sure of the datatype of a column . Hence I get an Exception while merging
#### Expected Output
What I Propose is we could have a parameter having ignore_data_type=true in the merge . When its true We could mandatorily cast the column of right_dataframe to the data type of left one and Proceed. Hence we could avoid this Exception.

#### Output of ``pd.show_versions()``

<details>
    Age    Name  score
0  13.0  Clarke     80
[paste the output of ``pd.show_versions()`` here leaving a blank line after the details tag]

</details>
