Allow Starlette 0.45 and 0.46

[musicinmybrain]

Starlette 0.45 drops Python 3.8 support, removes ExceptionMiddleware from starlette.exceptions, and removes WS_1004_NO_STATUS_RCVD and WS_1005_ABNORMAL_CLOSURE: https://github.com/encode/starlette/releases/tag/0.45.0

Starlette 0.46 renames max_file_size to spool_max_size in MultiPartParser: https://github.com/encode/starlette/releases/tag/0.46.0

None of that should affect openapi-core.

---

Even with this PR, Starlette would still be stuck at 0.44.0 in poetry.lock until openapi-core drops support for Python 3.8.

I didn’t try to drop Python 3.8 support in this PR, but just to check, I tried a local experiment:

diff --git a/pyproject.toml b/pyproject.toml
index 8132fd5..16369f9 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -47,7 +47,6 @@ classifiers = [
     "Topic :: Software Development :: Libraries :: Python Modules",
     "Operating System :: OS Independent",
     "Programming Language :: Python :: 3",
-    "Programming Language :: Python :: 3.8",
     "Programming Language :: Python :: 3.9",
     "Programming Language :: Python :: 3.10",
     "Programming Language :: Python :: 3.11",
@@ -60,7 +59,7 @@ include = [
 ]
 
 [tool.poetry.dependencies]
-python = "^3.8.0"
+python = "^3.9.0"
 django = {version = ">=3.0", optional = true}
 falcon = {version = ">=3.0", optional = true}
 flask = {version = "*", optional = true}

I then ran poetry update starlette and confirmed that the tests do still pass with Starlette 0.46.1.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 90.62%. Comparing base (ca6044e) to head (c9ba8eb).
Report is 16 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master     #977   +/-   ##
=======================================
  Coverage   90.62%   90.62%           
=======================================
  Files         150      150           
  Lines        4374     4374           
  Branches      532      532           
=======================================
  Hits         3964     3964           
  Misses        318      318           
  Partials       92       92           

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