Enhance DOI parser to deal with special characters

[AbdAlRahmanGad]

Fixes #10985

Some of the DOI links are not working because it has some special characters in it.
For example 10.1007/978-3-030-02671-4\_7 it has an extra backslash '\'.
I tried to fix the general problem instead of just the backslashes so I tried to eliminate all unsafe character

In the code I added them to the CHARS_TO_REMOVE regex variable.
as for '^' I handled it alone because the formatter is replacing any ^ + number with the superscript of the the number
for example: 10^34 -> 10³4

Mandatory checks

• Change in CHANGELOG.md described in a way that is understandable for the average user (if applicable)
• Tests created for changes (if applicable)
• Manually tested changed features in running JabRef (always required)
• Screenshots added in PR description (for UI changes)
• Checked developer's documentation: Is the information available and up to date? If not, I outlined it in this pull request.
• Checked documentation: Is the information available and up to date? If not, I created an issue at https://github.com/JabRef/user-documentation/issues or, even better, I submitted a pull request to the documentation repository.

[koppor]

Thank you.

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