Update check_requirements() single install (#9353)

* Update `check_requirements()` single install

Faster install and better conflict resolution with single installation

Signed-off-by: Glenn Jocher <glenn.jocher@ultralytics.com>

* Update

* Update

* Update

Signed-off-by: Glenn Jocher <glenn.jocher@ultralytics.com>

val.py

@@ -301,7 +301,7 @@ def run(
             json.dump(jdict, f)
 
         try:  # https://github.com/cocodataset/cocoapi/blob/master/PythonAPI/pycocoEvalDemo.ipynb
-            check_requirements(['pycocotools'])
+            check_requirements('pycocotools')
             from pycocotools.coco import COCO
             from pycocotools.cocoeval import COCOeval
 
@@ -360,7 +360,7 @@ def parse_opt():
 
 
 def main(opt):
-    check_requirements(requirements=ROOT / 'requirements.txt', exclude=('tensorboard', 'thop'))
+    check_requirements(exclude=('tensorboard', 'thop'))
 
     if opt.task in ('train', 'val', 'test'):  # run normally
         if opt.conf_thres > 0.001:  # https://github.com/ultralytics/yolov5/issues/1466