Fix precompiles build with solana-rent 3.x

[rolnimar]

Summary

Fix the precompiles feature build when litesvm resolves solana-rent 3.0.0.

Problem

litesvm declares:

solana-rent = "3.0"

but the precompiles path currently uses:

solana_rent::DEFAULT_LAMPORTS_PER_BYTE

That constant is not available in solana-rent 3.0.0, so precompiles fails to compile in a valid dependency resolution within the declared supported range.

## Why this fix is correct

The value is assigned to:

rent_account.lamports_per_byte_year

so solana_rent::DEFAULT_LAMPORTS_PER_BYTE_YEAR is the correct constant for that field.

This change keeps the fix narrowly scoped to that one issue and restores compatibility across the declared 3.x support range.

[kevinheavey]

slop