Fix deprecations in Julia 1.12

[devmotion]

Fixes #35.

To demonstrate that the PR actually fixes the issue and to avoid regressions, I enabled --depwarn=error for the tests. The last CI log on master shows the deprecations (e.g. https://github.com/SciML/FindFirstFunctions.jl/actions/runs/17587897576/job/49960746174?pr=36#step:6:102) whereas tests in this PR pass and (of course) CI logs don't show any deprecation warnings.

[Copilot]

Pull Request Overview

This PR fixes Julia 1.12 deprecation warnings related to LLVM IR generation by adapting the inline assembly code to use the new pointer syntax required in Julia 1.12+. The changes ensure compatibility across Julia versions while enabling strict deprecation checking in CI.

• Introduces version-dependent LLVM IR generation using conditional compilation based on Julia version
• Refactors the _findfirstequal function to use dynamic IR string construction instead of hardcoded LLVM assembly
• Enables strict deprecation checking in CI with --depwarn=error and adds "min" version testing

Reviewed Changes

Copilot reviewed 2 out of 3 changed files in this pull request and generated 3 comments.

File	Description
src/FindFirstFunctions.jl	Updates LLVM IR generation to support both old and new pointer syntax based on Julia version
.github/workflows/Tests.yml	Adds minimum Julia version testing and enables strict deprecation warnings

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