change AWS and GTTS max_chars

[swoker]

Description

previously aws TTS did not read out comments correctly and only made weird sounds with super short mp3s. This fixes the problem and allows the full comment to be read.

Issue Fixes

None

Checklist:

• I am pushing changes to the develop branch
• I am using the recommended development environment
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have formatted and linted my code using python-black and pylint
• I have cleaned up unnecessary files
• My changes generate no new warnings
• My changes follow the existing code-style
• My changes are relevant to the project

Any other information (e.g how to test the changes)

None

[callumio]

Is that the max character or an arbitrary number? It was set to 0 (infinite) originally as I can't test on AWS

[swoker]

(I checked a different source before and didn't realize the 100k limit is only for async calls which is not used here, so I updated it to 3k)
3000 chars is the max limit for the synchronous API call: https://docs.aws.amazon.com/polly/latest/dg/asynchronous.html

using max_chars=0 only sends empty strings to AWS and thus produces weird sounds. This commit fixes that

[swoker]

PS: Saw a similar problem in #1036 and fixed the max_chars for GTTS as well.
Text limit should be 5000, as seen on https://translate.google.com/