python3-cbor2: Install docs/usage.rst for ptests

tests/test_sequence_docs.py executes the code examples embedded in
docs/usage.rst, resolved relative to the tests directory. The file was
not installed, so all 26 tests in it failed with:

  FileNotFoundError: [Errno 2] No such file or directory:
  '/usr/lib/python3-cbor2/ptest/docs/usage.rst'

Signed-off-by: Khem Raj <khem.raj@oss.qualcomm.com>

meta-python/recipes-devtools/python/python3-cbor2_6.2.0.post2.bb

@@ -11,6 +11,10 @@ CARGO_SRC_DIR = "rust"
 
 require ${BPN}-crates.inc
 
+do_install_ptest:append() {
+    install -Dm 0644 ${S}/docs/usage.rst ${D}${PTEST_PATH}/docs/usage.rst
+}
+
 RDEPENDS:${PN}-ptest += " \
     python3-hypothesis \
     python3-tzdata \