Fix cmake command by adding missing quotes to FindSSE

[gregtatum]

Description

On an Apple arm64 build, I got an error running cmake. CPUINFO is a blank string. Since it's not in quotes, the argument list is too small creating an error.

CMake Error at cmake/FindSSE.cmake:95 (STRING):
  STRING sub-command REGEX, mode REPLACE needs at least 6 arguments total to
  command.
Call Stack (most recent call first):
  CMakeLists.txt:208 (include)

List of changes:

• Added quotes similar to the other uses.

Added dependencies: none

How to test

Run cmake on a known good machine. make test worked for me, but ./run_mrt.sh did not. I have another branch with other fixes to get it work on macOS arm64 CPU build. I don't know that it's expected for ./run_mrt.sh to actually work in this configuration.

Checklist

• I have tested the code manually
• I have run regression tests
• I have read and followed CONTRIBUTING.md
• I have updated CHANGELOG.md