CI: crux-llvm nightly Docker job is broken

[RyanGlScott]

The changes from #1256 inadvertently broke the nightly crux-llvm Docker job, as seen here:

#31 45.61           clang-range=recent-clang
#31 45.61             z3 4.8.14
#31 45.61               write-stdout
#31 45.61                 write-stdout crux run:                   OK
#31 45.61                 write-stdout crux output:                FAIL
#31 45.61                   test/Test.hs:326:
#31 45.61                   MISMATCH for expected (test-data/golden/stdio/write-stdout.z3.good)
#31 45.61                              and actual (test-data/golden/stdio/write-stdout.z3.z3.out) output:
#31 45.61                       F-expect>|output
#31 45.61                       F-actual>|clang-12: readCreateProcessWithExitCode: posix_spawnp: does not exist (No such file or directory)
#31 45.61                       F-expect>|[Crux] Overall status: Valid.
#31 45.61                   
#31 45.61                   Use -p '/loop-merging=loopmerge.clang-range=recent-clang.z3 4.8.14.write-stdout.write-stdout crux output/' to rerun this test only.
#31 45.61 
#31 45.61 1337 out of 2335 tests failed (6.12s)
#31 45.61 
#31 45.61 Test suite crux-llvm-test: FAIL
#31 45.61 Test suite logged to:
#31 45.61 /crux-llvm/build/dist-newstyle/build/x86_64-linux/ghc-9.4.8/crux-llvm-0.9.0.99/t/crux-llvm-test/test/crux-llvm-0.9.0.99-crux-llvm-test.log
#31 45.61 0 of 1 test suites (0 of 1 test cases) passed.
#31 ERROR: process "/bin/sh -c cabal v2-test crux-llvm" did not complete successfully: exit code: 1

Judging from the clang-12: readCreateProcessWithExitCode: posix_spawnp: does not exist (No such file or directory) part of the error message, the Dockerfile is expecting clang-12 when it should actually be looking for clang-14.