build(deps): bump h2 to 4.2.0 (#11437)

## Problem

We switched `h2` from 4.1.0 to a git commit to fix stubgen (in
https://github.com/neondatabase/neon/pull/10491). `h2` 4.2.0 was
released soon after that, so we can switch back to a pinned version.

Expected no changes, as 4.2.0 is the right next commit after the commit
we currently use:
dacd614fed%5E

## Summary of changes
- Bump `h2` to 4.2.0

poetry.lock

@@ -1,4 +1,4 @@
-# This file is automatically @generated by Poetry 2.1.1 and should not be changed by hand.
+# This file is automatically @generated by Poetry 2.1.2 and should not be changed by hand.
 
 [[package]]
 name = "aiohappyeyeballs"
@@ -1286,24 +1286,20 @@ files = [
 
 [[package]]
 name = "h2"
-version = "4.1.0"
+version = "4.2.0"
 description = "Pure-Python HTTP/2 protocol implementation"
 optional = false
 python-versions = ">=3.9"
 groups = ["main"]
-files = []
-develop = false
+files = [
+    {file = "h2-4.2.0-py3-none-any.whl", hash = "sha256:479a53ad425bb29af087f3458a61d30780bc818e4ebcf01f0b536ba916462ed0"},
+    {file = "h2-4.2.0.tar.gz", hash = "sha256:c8a52129695e88b1a0578d8d2cc6842bbd79128ac685463b887ee278126ad01f"},
+]
 
 [package.dependencies]
 hpack = ">=4.1,<5"
 hyperframe = ">=6.1,<7"
 
-[package.source]
-type = "git"
-url = "https://github.com/python-hyper/h2"
-reference = "HEAD"
-resolved_reference = "0b98b244b5fd1fe96100ac14905417a3b70a4286"
-
 [[package]]
 name = "hpack"
 version = "4.1.0"
@@ -3844,4 +3840,4 @@ cffi = ["cffi (>=1.11)"]
 [metadata]
 lock-version = "2.1"
 python-versions = "^3.11"
-content-hash = "fb50cb6b291169dce3188560cdb31a14af95647318f8f0f0d718131dbaf1817a"
+content-hash = "7ab1e7b975af34b3271b7c6018fa22a261d3f73c7c0a0403b6b2bb86b5fbd36e"