Use a global workflow variable to define the "Draft 4" compatible version of ajv-cli

The ajv-cli tool is used for validation of data files against their JSON schema.

In general, it is preferable, and for some schemas even mandatory, to use the modern versions of ajv-cli. However,
support for the "Draft 4" schema specification was dropped in ajv-cli version 4.0.0. So when working with JSON schemas
that specify that draft, it is necessary to use ajv-cli 3.3.0, the last compatible version.

Such schemas are relatively common, likely partly due to the Schema Store's policy that "Draft 4" be used whenever
possible. Having this version defined in a single place makes taskfiles with multiple tasks subject to this somewhat
esoteric (and thus requiring an explanatory comment) information a bit cleaner.

Author: per1234

Taskfile.yml

@@ -1,5 +1,9 @@
 version: "3"
 
+vars:
+  # Last version of ajv-cli with support for the JSON schema "Draft 4" specification
+  SCHEMA_DRAFT_4_AJV_CLI_VERSION: 3.3.0
+
 tasks:
   check:
     desc: Check for problems with the project
@@ -110,8 +114,6 @@ tasks:
   dependabot:validate:
     desc: Validate Dependabot configuration files against their JSON schema
     vars:
-      # Last version with support for draft-04, used by Dependabot schema
-      AJV_CLI_VERSION: 3.3.0
       # Source: https://github.com/SchemaStore/schemastore/blob/master/src/schemas/json/dependabot-2.0.json
       SCHEMA_URL: https://json.schemastore.org/dependabot-2.0
       SCHEMA_PATH:
@@ -120,7 +122,7 @@ tasks:
     cmds:
       - wget --quiet --output-document="{{.SCHEMA_PATH}}" {{.SCHEMA_URL}}
       - |
-        npx ajv-cli@{{.AJV_CLI_VERSION}} validate \
+        npx ajv-cli@{{.SCHEMA_DRAFT_4_AJV_CLI_VERSION}} validate \
           --all-errors \
           -s "{{.SCHEMA_PATH}}" \
           -d "{{.DATA_PATH}}"
@@ -342,8 +344,6 @@ tasks:
   npm:validate:
     desc: Validate npm configuration files against their JSON schema
     vars:
-      # Last version with support for draft-04, used by the `package.json` schema
-      AJV_CLI_VERSION: 3.3.0
       # Source: https://github.com/SchemaStore/schemastore/blob/master/src/schemas/json/package.json
       SCHEMA_URL: https://json.schemastore.org/package.json
       SCHEMA_PATH:
@@ -382,7 +382,7 @@ tasks:
       - wget --quiet --output-document="{{.SEMANTIC_RELEASE_SCHEMA_PATH}}" {{.SEMANTIC_RELEASE_SCHEMA_URL}}
       - wget --quiet --output-document="{{.STYLELINTRC_SCHEMA_PATH}}" {{.STYLELINTRC_SCHEMA_URL}}
       - |
-        npx ajv-cli@{{.AJV_CLI_VERSION}} validate \
+        npx ajv-cli@{{.SCHEMA_DRAFT_4_AJV_CLI_VERSION}} validate \
           --all-errors \
           -s "{{.SCHEMA_PATH}}" \
           -r "{{.AVA_SCHEMA_PATH}}" \

workflow-templates/assets/check-npm-task/Taskfile.yml

@@ -1,13 +1,15 @@
 # See: https://taskfile.dev/#/usage
 version: "3"
 
+vars:
+  # Last version of ajv-cli with support for the JSON schema "Draft 4" specification
+  SCHEMA_DRAFT_4_AJV_CLI_VERSION: 3.3.0
+
 tasks:
   # Source: https://github.com/arduino/tooling-project-assets/blob/main/workflow-templates/assets/check-npm-task/Taskfile.yml
   npm:validate:
     desc: Validate npm configuration files against their JSON schema
     vars:
-      # Last version with support for draft-04, used by the `package.json` schema
-      AJV_CLI_VERSION: 3.3.0
       # Source: https://github.com/SchemaStore/schemastore/blob/master/src/schemas/json/package.json
       SCHEMA_URL: https://json.schemastore.org/package.json
       SCHEMA_PATH:
@@ -46,7 +48,7 @@ tasks:
       - wget --quiet --output-document="{{.SEMANTIC_RELEASE_SCHEMA_PATH}}" {{.SEMANTIC_RELEASE_SCHEMA_URL}}
       - wget --quiet --output-document="{{.STYLELINTRC_SCHEMA_PATH}}" {{.STYLELINTRC_SCHEMA_URL}}
       - |
-        npx ajv-cli@{{.AJV_CLI_VERSION}} validate \
+        npx ajv-cli@{{.SCHEMA_DRAFT_4_AJV_CLI_VERSION}} validate \
           --all-errors \
           -s "{{.SCHEMA_PATH}}" \
           -r "{{.AVA_SCHEMA_PATH}}" \