fix ISL to build under conan 2.0

[doocman]

Specify library name and version: ISL/0.24.0+0.25.0+0.26.0

I want to be able to compile GCC (for different cross-compiling targets including AVR) using conan, and I thought I'd try to help migrating the dependencies to conan 2.0 (as it is nice knowing I can get it to work with the most up-to-date tools)

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• I've read the contributing guidelines.
• I've used a recent Conan client version close to the currently deployed.
• I've tried at least one configuration locally with the conan-center hook activated. - I have conan 2.0 only, and the hooks seems to work differently (?). I have tried both 0.24 and 0.26 though..

[CLAassistant]

All committers have signed the CLA.

[ghost]

I detected other pull requests that are modifying isl/all recipe:

• ISL Conan 2.0 compatibility #14916

This message is automatically generated by https://github.com/ericLemanissier/conan-center-conflicting-prs so don't hesitate to report issues/improvements there.

[conan-center-bot]

Conan v1 pipeline ❌

Sorry, the build is only launched for Access Request users. You can request access writing in this issue.

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Conan v2 pipeline ❌

Note: Conan v2 builds may be required once they are on the v2 ready list

The v2 pipeline failed. Please, review the errors and note this will be required for pull requests to be merged in the near future.

See details:

Sorry, the build is only launched for Access Request users. You can request access writing in this issue.

[doocman]

The mentioned PR is more complete, I'll close this one.