restrict deepspeed version in CI (#8951)

Author: awaelchli

.azure-pipelines/gpu-tests.yml

@@ -51,7 +51,7 @@ jobs:
     - bash: |
         python -c "fname = 'requirements/extra.txt' ; lines = [line for line in open(fname).readlines() if 'horovod' not in line] ; open(fname, 'w').writelines(lines)"
         pip install fairscale>=0.3.4
-        pip install "deepspeed>=0.4.3, !=0.4.4, !=0.4.5" # FIXME: bug with 0.4.4 and 0.4.5
+        pip install "deepspeed==0.4.3" # FIXME: bug with >= 0.4.4
         pip install . --requirement requirements/devel.txt
         pip list
       displayName: 'Install dependencies'