chore(deps): update dependency httpx to ^0.26.0 (#292)

Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

Author: renovate[bot]

poetry.lock

@@ -39,7 +39,7 @@ pytest-httpbin = "^2.0.0"
 pytest-randomly = "^3.15.0"
 requests = "^2.26.0"
 starlette = "^0.34.0"
-httpx = "^0.25.0"
+httpx = "^0.26.0"
 # See https://github.com/postmanlabs/httpbin/pull/674
 httpbin = { git = "https://github.com/maximino-dev/httpbin.git", rev = "651c03a73" }