Run unit tests depending on Z3 on Windows CI job

As these now work, they should be tested in CI.

Author: thomasspriggs

.github/workflows/pull-request-checks.yaml

@@ -482,6 +482,7 @@ jobs:
       - name: Run CBMC and JBMC unit tests
         run: |
           make CXX=clcache BUILD_ENV=MSVC -C unit      test
+          make CXX=clcache BUILD_ENV=MSVC -C unit test TAGS="[z3]"
           make CXX=clcache BUILD_ENV=MSVC -C jbmc/unit test
       - name: Run CBMC regression tests
         run: make CXX=clcache BUILD_ENV=MSVC -C regression test