update links to images for welcome bot

Author: reshamas

.github/config.yml

@@ -4,8 +4,8 @@
 
 # Comment to be posted to on first time issues
 newIssueWelcomeComment: |
-  [![Welcome Banner](https://zenodo.org/api/iiif/v2/0c0188d3-d03c-4830-a6e3-00405f5c22fa:8ff47a85-7250-4d86-8e48-2f346b48b2c1:BannerWelcome.jpg/full/750,/0/default.jpg)](https://zenodo.org/record/3695300)
-
+  ![Welcome Banner](https://github.com/scikit-learn/blog/blob/main/welcome-bot/BannerWelcome.jpg)
+  
   :tada: Welcome to _scikit-learn Blog_! :tada:
   We're really excited to have your input into the project! :sparkling_heart:
 
@@ -16,7 +16,7 @@ newIssueWelcomeComment: |
 
 # Comment to be posted to on PRs from first time contributors in your repository
 newPRWelcomeComment: |
-  [![Thank You Banner](https://zenodo.org/api/iiif/v2/0c0188d3-d03c-4830-a6e3-00405f5c22fa:7fbd97cf-283b-480c-b8e1-11866e26245c:BannerThanks.jpg/full/750,/0/default.jpg)](https://zenodo.org/record/3695300)
+  ![Thank You Banner](https://github.com/scikit-learn/blog/blob/main/welcome-bot/BannerThanks.jpg)
 
   :sparkling_heart: Thanks for opening this pull request! :sparkling_heart:
   _scikit-learn_ community really appreciates your time and effort to contribute to the project.
@@ -27,7 +27,7 @@ newPRWelcomeComment: |
 
 # Comment to be posted to on pull requests merged by a first time user
 firstPRMergeComment: |
-  [![Congratulations Banner](https://zenodo.org/api/iiif/v2/0c0188d3-d03c-4830-a6e3-00405f5c22fa:32fbdb89-ae1b-434e-830c-88ade86724cc:BannerCongratulations.jpg/full/750,/0/default.jpg)](https://zenodo.org/record/3695300)
+  ![Congratulations Banner](https://github.com/scikit-learn/blog/blob/main/welcome-bot/BannerCongratulations.jpg)
 
   Congrats on merging your first pull request! :tada:
   We here at _scikit-learn_ are proud of you! :sparkling_heart: