Bump ast-serialize to 0.9.0 (#21929)

I intentionally not bumping cache version yet, to make sure backwards
compatibility is OK.

mypy-requirements.txt

diff --git a/mypy-requirements.txt b/mypy-requirements.txt
index edb73a7..83f6f4d 100644
--- a/mypy-requirements.txt
+++ b/mypy-requirements.txt
@@ -6,4 +6,4 @@
 pathspec>=1.0.0
 tomli>=1.1.0; python_version<'3.11'
 librt>=0.15.0; platform_python_implementation != 'PyPy'
-ast-serialize>=0.8.0,<1.0.0
+ast-serialize>=0.9.0,<1.0.0

pyproject.toml

diff --git a/pyproject.toml b/pyproject.toml
index f5de683..8fc9f9e 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -15,7 +15,7 @@
     "types-psutil",
     "types-setuptools",
     # required to work around a mypyc import bug
-    "ast-serialize>=0.8.0,<1.0.0",
+    "ast-serialize>=0.9.0,<1.0.0",
 ]
 build-backend = "setuptools.build_meta"
 
@@ -59,7 +59,7 @@
   "pathspec>=1.0.0",
   "tomli>=1.1.0; python_version<'3.11'",
   "librt>=0.15.0; platform_python_implementation != 'PyPy'",
-  "ast-serialize>=0.8.0,<1.0.0",
+  "ast-serialize>=0.9.0,<1.0.0",
 ]
 dynamic = ["version"]
 

test-data/unit/native-parser.test

diff --git a/test-data/unit/native-parser.test b/test-data/unit/native-parser.test
index 5d78ad6..83dbb3e 100644
--- a/test-data/unit/native-parser.test
+++ b/test-data/unit/native-parser.test
@@ -1717,7 +1717,7 @@
   ExpressionStmt:2(
     BytesExpr(foobar))
   ExpressionStmt:3(
-    BytesExpr(x\\n\\\')))
+    BytesExpr(x\\n\\')))
 
 [case testBytesLiteralWithEscapes]
 b'\r\n\t\x2f\xbe'

test-requirements.txt

diff --git a/test-requirements.txt b/test-requirements.txt
index a6e6dd5..5e5cde3 100644
--- a/test-requirements.txt
+++ b/test-requirements.txt
@@ -4,7 +4,7 @@
 #
 #    pip-compile --allow-unsafe --output-file=test-requirements.txt --strip-extras test-requirements.in
 #
-ast-serialize==0.8.0
+ast-serialize==0.9.0
     # via -r mypy-requirements.txt
 attrs==26.1.0
     # via -r test-requirements.in