[roll third_party/pigweed] pw_env_setup: Update mypy to 0.991 and mypy-protobuf to 3.3.0

The setup.cfg file requires only mypy-protobuf>=3.2.0 but we pin down
3.3.0 for pigweed in the constraint.list file.

Workaround the issues found by the new mypy.

Test: pw presubmit
Original-Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/126270

https://pigweed.googlesource.com/pigweed/pigweed
third_party/pigweed Rolled-Commits: e9e9157cddd08c5..dc0e4b207516fe3
Roller-URL: https://ci.chromium.org/b/8792222106625079601
GitWatcher: ignore
CQ-Do-Not-Cancel-Tryjobs: true
Change-Id: I7679a47767a1d08db6f4b21d459be0cfc0fd8db4
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/experimental/+/126429
Bot-Commit: Pigweed Integration Roller <pigweed-integration-roller@pigweed.google.com.iam.gserviceaccount.com>
Commit-Queue: Pigweed Integration Roller <pigweed-integration-roller@pigweed.google.com.iam.gserviceaccount.com>
diff --git a/third_party/pigweed b/third_party/pigweed
index e9e9157..dc0e4b2 160000
--- a/third_party/pigweed
+++ b/third_party/pigweed
@@ -1 +1 @@
-Subproject commit e9e9157cddd08c5d0d2ed167efa9a9b3310d1cb0
+Subproject commit dc0e4b207516fe383b14c1380f7d357d4e0105cb