Improved code copy behaviour

[ShUl0w]

Resolves #67

Context

This PR removes the coding language from the copied code block, and improves handling of trailing markdown syntax.

Steps to reproduce

Prompt: A regex in python to replace numbers. Do not give an explanation.

Result (> to prevent markdown formatting):

python
import re

text = "Your text with numbers like 123."
result = re.sub(r'\d+', '', text)
print(result)
>```

Current behaviour

The text that's being copied to the clipboard is (> to prevent markdown formatting):

python
import re

text = "Your text with numbers like 123."
result = re.sub(r'\d+', '', text)
print(result)
>```

New behaviour

The text that's being copied to the clipboard is:

import re

text = "Your text with numbers like 123."
result = re.sub(r'\d+', '', text)
print(result)