wreq: stage README.md/Cargo.toml/LICENSE for tests that open them by path

multipart_test.py, request_test.py and response_test.py all build request
bodies from these three repo-root files via a path relative to the repo
root; CIBW_TEST_SOURCES only staged tests/, so every one of those tests hit
a FileNotFoundError, surfaced as a DecodingError once that exception inside
the async body-stream left httpbin nothing to respond with.

Author: luhenry

.github/workflows/build-wreq.yml

@@ -98,7 +98,13 @@ jobs:
             CARGO_BUILD_JOBS=2
           # Upstream's tests job serves httpbin on localhost:8080 as a service container.
           CIBW_TEST_REQUIRES: pytest pytest-asyncio pytest-rerunfailures httpbin
-          CIBW_TEST_SOURCES: tests
+          # multipart_test.py, request_test.py and response_test.py open README.md,
+          # Cargo.toml and LICENSE by a path relative to the repo root (e.g.
+          # Path("./README.md"), open("README.md")) to build request bodies; without
+          # them staged in test_cwd every such test fails with a FileNotFoundError,
+          # surfaced as a DecodingError once that exception inside the async
+          # body-stream leaves httpbin nothing to respond with.
+          CIBW_TEST_SOURCES: tests README.md Cargo.toml LICENSE
           CIBW_TEST_COMMAND: >-
             python -m httpbin.core --port 8080 > httpbin.log 2>&1 & HTTPBIN_PID=$!;
             python -c "import wreq.wreq as m; assert m.__file__.endswith('.so'), m.__file__" &&