try github actions (#3679)

fixes #3583

.github/workflows/main.yml

+name: check_urls
+on: [push]
+jobs:
+  job:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v1
+      - uses: trilom/file-changes-action@v1.2.4
+        id: file_changes
+        with:
+          output: ''
+      - uses: ruby/setup-ruby@v1
+        with:
+          ruby-version: 2.4.1
+      - run: gem install awesome_bot
+      - run: for i in ${{ steps.file_changes.outputs.files_modified }}; do echo; echo "processing $i"; awesome_bot $i --allow-redirect --allow-dupe --skip-save-results; done

.travis.yml

@@ -12,13 +12,3 @@ jobs:
         - npm install -g free-programming-books-lint
       script:
         - fpb-lint .
-
-    -
-      language: ruby
-      if: commit_message =~ /check_urls=/
-      rvm: 2.4.1
-      before_script:
-        - gem install awesome_bot
-      script:
-        - INPUT=$(echo $TRAVIS_COMMIT_MESSAGE | awk -F= '{print $2}')
-        - for i in $INPUT; do echo "processing $i"; awesome_bot $i --allow-redirect --allow-dupe --skip-save-results; done

free-programming-books.md

@@ -306,7 +306,7 @@
 
 #### Algorithms & Data Structures
 
-* [A Field Guide To Genetic Programming](http://dces.essex.ac.uk/staff/rpoli/gp-field-guide/toc.html) - Riccardo Poli et al.
+* [A Field Guide To Genetic Programming](https://b-ok.cc/book/861921/18f698) - Riccardo Poli et al. (PDF)
 * [Algorithmic Graph Theory](http://code.google.com/p/graphbook/)
 * [Algorithms](https://en.wikibooks.org/wiki/Algorithms) - Wikibooks
 * [Algorithms, 4th Edition](http://algs4.cs.princeton.edu/home/) - Robert Sedgewick and Kevin Wayne