chore: downgrade to libc@0.2.174 (#15918)

### What does this PR try to resolve?

We have downgraded this in #15851
We should also let renovate ignore it.

This also again downgrades libc to 0.2.174 again.

See
<rust-lang/rust#146176 (comment)>.

Author: ehuss

.github/renovate.json5

@@ -8,6 +8,8 @@
   ignorePaths: [
     '**/tests/**',
   ],
+  // For why we ignore, see https://github.com/bytecodealliance/rustix/issues/1496
+  ignoreDeps: ['libc'],
   customManagers: [
     {
       customType: 'regex',