Pin (and fix?) mypy (#8755)

Author: NicolasHug

.github/workflows/lint.yml

@@ -72,7 +72,7 @@ jobs:
       script: |
         set -euo pipefail
 
-        export PYTHON_VERSION=3.9
+        export PYTHON_VERSION=3.11
         export GPU_ARCH_TYPE=cpu
         export GPU_ARCH_VERSION=''
 
@@ -83,7 +83,7 @@ jobs:
         conda activate ci
 
         echo '::group::Install lint tools'
-        pip install --progress-bar=off mypy
+        pip install --progress-bar=off "mypy==1.13.0"
         echo '::endgroup::'
 
         echo '::group::Lint Python types'

torchvision/models/maxvit.py

@@ -688,7 +688,7 @@ def __init__(
                     p_stochastic=p_stochastic[p_idx : p_idx + num_layers],
                 ),
             )
-            input_size = self.blocks[-1].grid_size
+            input_size = self.blocks[-1].grid_size  # type: ignore[assignment]
             p_idx += num_layers
 
         # see https://github.com/google-research/maxvit/blob/da76cf0d8a6ec668cc31b399c4126186da7da944/maxvit/models/maxvit.py#L1137-L1158