Postcss: fix failures processing .postcssrc.json #323

Job	Run time
Determine jobs to run	24s
Check next-swc	2m 21s
Turbopack rust check	1m 24s
Turbopack TypeScript files	0s
Turbopack rust clippy	1m 36s
Turbopack Rust testing on ubuntu	4m 57s
Turbopack Rust testing on macos	37m 32s
Turbopack Rust testing on windows	30m 16s
Turbopack Rust testing benchmarks on linux / Test	2m 31s
Turbopack Rust testing benchmarks on macos / Test	17m 7s
Ok	6s
Upload Test results	29s
Done	5s
Cleanup / cleanup	3s
	1h 38m 51s

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