feat(yamllint): add .bundle/ to the default ignore list

Justification given here:

* saltstack-formulas/prometheus-formula#60 (comment)

.yamllint

@@ -5,15 +5,17 @@
 extends: 'default'
 
 # Files to ignore completely
-# 1. All YAML files under directory `.cache/`, introduced during the GitLab CI run
-# 2. All YAML files under directory `.git/`
-# 3. All YAML files under directory `node_modules/`, introduced during the Travis run
-# 4. Any SLS files under directory `test/`, which are actually state files
-# 5. Any YAML files under directory `.kitchen/`, introduced during local testing
-# 6. `kitchen.vagrant.yml`, which contains Embedded Ruby (ERB) template syntax
-# 7. All Jinja templates under `ssf/files/` (result in `yamllint` syntax errors)
+# 1. All YAML files under directory `.bundle/`, introduced if gems are installed locally
+# 2. All YAML files under directory `.cache/`, introduced during the CI run
+# 3. All YAML files under directory `.git/`
+# 4. All YAML files under directory `node_modules/`, introduced during the CI run
+# 5. Any SLS files under directory `test/`, which are actually state files
+# 6. Any YAML files under directory `.kitchen/`, introduced during local testing
+# 7. `kitchen.vagrant.yml`, which contains Embedded Ruby (ERB) template syntax
+# 8. All Jinja templates under `ssf/files/` (result in `yamllint` syntax errors)
 #    Not disabling via. `*.yml` since we may end up with non-Jinja YAML files here
 ignore: |
+  .bundle/
   .cache/
   .git/
   node_modules/

ssf/defaults.yaml

@@ -237,6 +237,7 @@ ssf_node_anchors:
           extends: 'default'
           ignore:
             default:
+              - '.bundle/'
               - '.cache/'
               - '.git/'
               - 'node_modules/'

ssf/files/default/.yamllint

@@ -15,19 +15,20 @@ ignore: |
 extends: '{{ yamllint.extends }}'
 
 # Files to ignore completely
-# 1. All YAML files under directory `.cache/`, introduced during the GitLab CI run
-# 2. All YAML files under directory `.git/`
-# 3. All YAML files under directory `node_modules/`, introduced during the Travis run
-# 4. Any SLS files under directory `test/`, which are actually state files
-# 5. Any YAML files under directory `.kitchen/`, introduced during local testing
-# 6. `kitchen.vagrant.yml`, which contains Embedded Ruby (ERB) template syntax
+# 1. All YAML files under directory `.bundle/`, introduced if gems are installed locally
+# 2. All YAML files under directory `.cache/`, introduced during the CI run
+# 3. All YAML files under directory `.git/`
+# 4. All YAML files under directory `node_modules/`, introduced during the CI run
+# 5. Any SLS files under directory `test/`, which are actually state files
+# 6. Any YAML files under directory `.kitchen/`, introduced during local testing
+# 7. `kitchen.vagrant.yml`, which contains Embedded Ruby (ERB) template syntax
 {%- if semrel_formula == 'ssf' %}
-# 7. All Jinja templates under `ssf/files/` (result in `yamllint` syntax errors)
+# 8. All Jinja templates under `ssf/files/` (result in `yamllint` syntax errors)
 #    Not disabling via. `*.yml` since we may end up with non-Jinja YAML files here
 {%- elif semrel_formula == 'mysql' %}
-# 7. Any YAML files using Jinja (result in `yamllint` syntax errors)
+# 8. Any YAML files using Jinja (result in `yamllint` syntax errors)
 {%- elif semrel_formula in ['postgres', 'salt'] %}
-# 7. All YAML files heavily reliant on Jinja; these can be tackled in a subsequent PR
+# 8. All YAML files heavily reliant on Jinja; these can be tackled in a subsequent PR
 {%- endif %}
 {%- set yl_ignores = {'ignore':
   yamllint.ignore.default +