Use of deprecated `RandomStringUtils.randomAlphanumeric`

[johnthagen]

The automated JetBrains analysis result for the 1.6.6 release noted the following deprecated function call that should be replaced:

Deprecated method RandomStringUtils.randomAlphanumeric(int) is invoked in CppcheckInspection.checkFile(...)

clion-cppcheck/src/com/github/johnthagen/cppcheck/CppcheckInspection.java

Line 95 in 3359ea2

tempFile = FileUtil.createTempFile(RandomStringUtils.randomAlphanumeric(8) + "_", vFile.getName(), true);

[johnthagen]

CC @firewave