Make Type::write return correct value for rumqttd

[amokfa]

Type of change

write method wasn't returning the number of bytes read correctly for some types in rumqttd.

Checklist:

• Formatted with cargo fmt
• Make an entry to CHANGELOG.md if it's relevant to the users of the library. If it's not relevant mention why.

[coveralls]

Pull Request Test Coverage Report for Build 8243325619

Details

• 0 of 2 (0.0%) changed or added relevant lines in 2 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.003%) to 37.83%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
rumqttd/src/protocol/v4/connect.rs	0	1	0.0%
rumqttd/src/protocol/v5/connect.rs	0	1	0.0%

Totals
Change from base Build 8233430325:	0.003%
Covered Lines:	6254
Relevant Lines:	16532

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💛 - Coveralls

[swanandx]

thanks :) 🚀