Dockerfile torch fix (#987)

* add torch to requirements.txt at build time to force version to stick

* fix xformers check

* better handling of xformers based on installed torch version

* fix for ci w/o torch

.github/workflows/main.yml

@@ -27,7 +27,7 @@ jobs:
           - cuda: 118
             cuda_version: 11.8.0
             python_version: "3.10"
-            pytorch: 2.1.0
+            pytorch: 2.1.1
             axolotl_extras:
     runs-on: [self-hosted, gpu, docker]
     steps:
@@ -80,7 +80,7 @@ jobs:
           - cuda: 118
             cuda_version: 11.8.0
             python_version: "3.10"
-            pytorch: 2.1.0
+            pytorch: 2.1.1
             axolotl_extras:
     runs-on: [self-hosted, gpu, docker]
     steps: