v0.1.3 — Some cleanup here and there

Highlights:

✅ Lowered Go version requirement from 1.24.1 → 1.18, allowing more developers to build from source.
🔧 CI Matrix enhanced: Now tests across Go 1.18, 1.20, 1.22, and 1.24, improving backward compatibility assurance.
🛡️ Failsafe restrictions: If no sandbox rules are provided, Landrun now applies a default deny-all sandbox, preventing accidental unsafe execution.
📦 Added --version flag support via embedded Version constant.
📉 Downgraded golang.org/x/sys to v0.26.0 for broader compatibility.

Dev / Internal:
🧪 go mod tidy added to GitHub Actions for dependency hygiene.
🧼 YAML cleanup and quoting for Go versions in CI matrix.
🧱 Version tag now shown properly in the CLI (landrun --version).