patch: work around pip's secure-install bug; bump version

- upstream issue: https://github.com/pypa/pip/issues/9644
- runs tests within a container, uses the same `dockerfile`
- ignores `pdm.lock`, removes `requirement.txt`
- update manual contribution steps
- bumps project version

**Related Items**

_Issues_

- Closes #137

compose.yml

@@ -0,0 +1,11 @@
+# for CI testing
+services:
+  waka-readme:
+    env_file:
+      - .env.template
+    build:
+      context: .
+      dockerfile: dockerfile
+    image: waka-readme:testing
+    container_name: WakaReadmeTesting
+    command: python -m unittest discover