[INFRA] Relax line length limit for linting YAML files (#673)

* MNT: Relax line length limit in YAML

* MNT: Ignore pycache in tools dir

* CI: Update configuration based on Travis validator

Also bump Python version and cache pip

.travis.yml

@@ -1,8 +1,11 @@
-matrix:
+os: linux
+dist: focal
+language: shell
+
+jobs:
   include:
     - language: node_js
-      node_js:
-        - "10"
+      node_js: 10
       cache:
         directories:
         - node_modules # NPM packages
@@ -11,7 +14,8 @@ matrix:
       script:
         - remark src/*.md src/*/*.md --frail
     - language: python
-      python: 3.7
+      python: 3.9
+      cache: pip
       install:
         - pip install yamllint
       script:

.yamllint.yml

@@ -0,0 +1,5 @@
+extends: default
+
+rules:
+  line-length:
+    max: 99

tools/.gitignore

@@ -0,0 +1 @@
+__pycache__