Add signatures for commons-io 2.18.0

[kwin]

Commons IO 2.18.0 has been released Nov 2024: https://commons.apache.org/proper/commons-io/changes-report.html#a2.18.0.

Currently depending on this version fails as no signature for this version ships with forbidden-apis.
At first glance it doesn't look like new signature need to be applied for this version compared to https://github.com/policeman-tools/forbidden-apis/blob/main/src/main/resources/de/thetaphi/forbiddenapis/signatures/commons-io-unsafe-2.17.0.txt

[uschindler]

Will do this before release. No PR required.

[uschindler]

I checked the report for new signatures:
https://commons.apache.org/proper/commons-io/japicmp.html

This also makes sure that new version has no new violations!

I will go ahead and add a new empty signatures file!