fontique: Remove unsafe in fontconfig cache #161

Job	Run time
cargo test (windows-latest)	1m 30s
cargo test (macos-14)	50s
cargo check (msrv) (android) (armv7-linux-androideabi)	48s
cargo check (msrv) (windows-latest)	2m 1s
cargo test (ubuntu-latest)	37s
cargo clippy (windows-latest)	2m 36s
cargo check (msrv) (macos-14)	1m 3s
cargo check (msrv) (android) (aarch64-linux-android)	47s
cargo clippy (macos-14)	1m 15s
cargo check (msrv) (ubuntu-latest)	58s
cargo check (msrv) (android) (x86_64-linux-android)	47s
cargo clippy (ubuntu-latest)	1m 9s
cargo clippy (android) (armv7-linux-androideabi)	1m 5s
cargo clippy (android) (aarch64-linux-android)	1m 5s
cargo doc (windows-latest)	2m 4s
cargo clippy (android) (x86_64-linux-android)	1m 4s
cargo fmt	10s
cargo doc (macos-14)	45s
cargo doc (ubuntu-latest)	28s
	21m 2s

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