update docker image to newer pytorch (#3680)

Co-authored-by: Mufei Li <mufeili1996@gmail.com>

docker/install/conda_env/torch_cpu_pip.txt

 --find-links https://download.pytorch.org/whl/torch_stable.html
-torch==1.5.1+cpu
-torchvision==0.6.1+cpu
+torch==1.8.1+cpu
 pytest
 nose
 numpy

docker/install/conda_env/torch_gpu_pip.txt

 --find-links https://download.pytorch.org/whl/torch_stable.html
-torch==1.5.1+cu101
-torchvision==0.6.1+cu101
+torch==1.8.1+cu101
 pytest
 nose
 numpy

docker/pods/ci-compile-cpu.yaml

@@ -5,7 +5,7 @@ spec:
     runAsUser: 0
   containers:
   - name: dgl-ci-cpu-compile
-    image: dgllib/dgl-ci-cpu:conda
+    image: dgllib/dgl-ci-cpu:cu101_v220123
     imagePullPolicy: Always
     tty: true
     resources:

docker/pods/ci-compile-gpu.yaml

@@ -5,7 +5,7 @@ spec:
     runAsUser: 0
   containers:
   - name: dgl-ci-gpu-compile
-    image: dgllib/dgl-ci-gpu:conda
+    image: dgllib/dgl-ci-gpu:cu101_v220123
     imagePullPolicy: Always
     tty: true
     resources:

docker/pods/ci-cpu.yaml

@@ -5,7 +5,7 @@ spec:
     runAsUser: 0
   containers:
   - name: dgl-ci-cpu
-    image: dgllib/dgl-ci-cpu:conda
+    image: dgllib/dgl-ci-cpu:cu101_v220123
     imagePullPolicy: Always
     tty: true
     resources:

docker/pods/ci-gpu.yaml

@@ -5,7 +5,7 @@ spec:
     runAsUser: 0
   containers:
     - name: dgl-ci-gpu
-      image: dgllib/dgl-ci-gpu:conda
+      image: dgllib/dgl-ci-gpu:cu101_v220123
       imagePullPolicy: Always
       tty: true
       resources: