maint(common): Downgrade Crowdin GHA to v1.20.4

[darcywong00]

(updated to include current error)

I think this addresses #15392 (follows #15373 which didn't work)

See #12116, where the Crowdin CLI version 4.0+ is giving language mapping errors.
Log from a recent failing action:

STARTING CROWDIN ACTION
UPLOAD SOURCES
❌ Configuration file is invalid. Check the following parameters in your configuration file:
	- The mapping format is the following: crowdin_language_code: code_you_use. Check the full list of Crowdin language codes that can be used for mapping: https://developer.crowdin.com/language-codes.
	- The mapping format is the following: crowdin_language_code: code_you_use. Check the full list of Crowdin language codes that can be used for mapping: https://developer.crowdin.com/language-codes.
	- The mapping format is the following: crowdin_language_code: code_you_use. Check the full list of Crowdin language codes that can be used for mapping: https://developer.crowdin.com/language-codes.
	- The mapping format is the following: crowdin_language_code: code_you_use. Check the full list of Crowdin language codes that can be used for mapping: https://developer.crowdin.com/language-codes.
	- The mapping format is the following: crowdin_language_code: code_you_use. Check the full list of Crowdin language codes that can be used for mapping: https://developer.crowdin.com/language-codes.
	- The mapping format is the following: crowdin_language_code: code_you_use. Check the full list of Crowdin language codes that can be used for mapping: https://developer.crowdin.com/language-codes.
	- The mapping format is the following: crowdin_language_code: code_you_use. Check the full list of Crowdin language codes that can be used for mapping: https://developer.crowdin.com/language-codes.
	- The mapping format is the following: crowdin_language_code: code_you_use. Check the full list of Crowdin language codes that can be used for mapping: https://developer.crowdin.com/language-codes.
	- The mapping format is the following: crowdin_language_code: code_you_use. Check the full list of Crowdin language codes that can be used for mapping: https://developer.crowdin.com/language-codes.
	- The mapping format is the following: crowdin_language_code: code_you_use. Check the full list of Crowdin language codes that can be used for mapping: https://developer.crowdin.com/language-codes.
	- The mapping format is the following: crowdin_language_code: code_you_use. Check the full list of Crowdin language codes that can be used for mapping: https://developer.crowdin.com/language-codes.
	- The mapping format is the following: crowdin_language_code: code_you_use. Check the full list of Crowdin language codes that can be used for mapping: https://developer.crowdin.com/language-codes.
	- The mapping format is the following: crowdin_language_code: code_you_use. Check the full list of Crowdin language codes that can be used for mapping: https://developer.crowdin.com/language-codes.

Very unfortunate Crowdin doesn't tell us what langauge code it's failing on - even when I run the CLI in verbose mode. 😞

When #12116 gets resolved where we can use Crowdin CLI 4.0+, then we can update the GHA version.

Change

This workaround PR reverts the GitHub action to v1.20.4 which uses CLI 3.19.4.

Test-bot: skip
Build-bot: skip

[keymanapp-test-bot]

User Test Results

Test specification and instructions

User tests are not required

[mcdurdin]

I am concerned that this is a backwards step - downgrading a dependency/tool needs to be carefully considered because it locks us into an old version which will cause future maintenance headaches. Please do clearly outline the specific reason why we need to have an older version - including error messages and mitigation steps taken with the latest release.

[darcywong00]

Please do clearly outline the specific reason why we need to have an older version - including error messages and mitigation steps taken with the latest release.

I've updated the PR description with the error log and additional info

[darcywong00]

I'll hold off on merging this to see if it gets replaced by #15407

[darcywong00]

This can be abandoned. Replaced by #15407