Fix 'Possible OS Command Injection (CWE-78)' issue in src\fileProcessor.cpp

[CodeFactor](https://www.codefactor.io/repository/github/swiftraccoon/cpp-sdrtrunk-transcriber) found an issue: Possible OS Command Injection (CWE-78)

It's currently on:
[src\fileProcessor.cpp:114](https://www.codefactor.io/repository/github/swiftraccoon/cpp-sdrtrunk-transcriber/source/main/src/fileProcessor.cpp#L114)
Commit 9770ab0a43550c32af98210777d04c476efc47aa