docs: fix CHANGELOG nad pyproject.toml URLs in CONTRIBUTING.md (#184)

They were leading to Apify Python SDK, which is really confusing 😅

Author: tobice

CONTRIBUTING.md

@@ -84,19 +84,19 @@ so don't forget to describe the changes in the new version there.
 
 Beta release happens automatically after you merge a pull request or add a direct commit to the master branch. Before you do that check the following:
 
-- Make sure that in the [pyproject.toml](https://github.com/apify/apify-sdk-python/blob/master/pyproject.toml) a project version is set to the latest non-published version.
-- Describe your changes to the [CHANGELOG.md](https://github.com/apify/apify-sdk-python/blob/master/CHANGELOG.md) in the section with the latest non-published version.
+- Make sure that in the [pyproject.toml](./pyproject.toml) a project version is set to the latest non-published version.
+- Describe your changes to the [CHANGELOG.md](./CHANGELOG.md) in the section with the latest non-published version.
 
 ### Production release checklist
 
 Production release happens after the GitHub release is created. Before you do that check the following:
 
 - Make sure [here](https://pypi.org/project/apify-client/#history) that the beta release with the latest commit is successfully deployed.
-- Make sure that all changes that happened from the last production release are described in the [CHANGELOG.md](https://github.com/apify/apify-sdk-python/blob/master/CHANGELOG.md) (it's okay to skip DX related changes, repo setup etc).
+- Make sure that all changes that happened from the last production release are described in the [CHANGELOG.md](./CHANGELOG.md) (it's okay to skip DX related changes, repo setup etc).
 - When drafting a new GitHub release:
     - Create a new tag in the format of `v1.2.3` targeting the master branch.
     - Fill in the release title in the format of `1.2.3`.
-    - Copy the changes from the [CHANGELOG.md](https://github.com/apify/apify-sdk-python/blob/master/CHANGELOG.md) and paste them into the release description. Make sure that all changes are properly categorized using headlines (`Added`, `Fixed` or `Internal changes`).
+    - Copy the changes from the [CHANGELOG.md](./CHANGELOG.md) and paste them into the release description. Make sure that all changes are properly categorized using headlines (`Added`, `Fixed` or `Internal changes`).
     - Check the "Set as the latest release" option.
 
 Currently, there is no explicit approval process, so when you are done with the checklist, proceed with the release.