fuzz: fix fuzz build

[manunio]

Hi, This PR attempts to fix failing fuzz builds at https://oss-fuzz-build-logs.storage.googleapis.com/index.html#nom, It was showing following error in build logs

Step #3 - "compile-libfuzzer-address-x86_64": �[0m�[1m�[38;5;9merror[E0618]�[0m�[0m�[1m: expected function, found `impl Parser<&str, Output = i64, Error = nom::error::Error<&str>>`�[0m

Note: I'm confused about the cosmetic part, following format changes were applied after running cargo +stable fmt

[coveralls]

Pull Request Test Coverage Report for Build 6787985074

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 62.376%

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Totals
Change from base Build 6789992865:	0.0%
Covered Lines:	1827
Relevant Lines:	2929

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💛 - Coveralls