Add warning in v3 about upcoming Docker removal in v4

.cirrus.star

@@ -1,4 +1,4 @@
-load("github.com/SonarSource/cirrus-modules@v2", "load_features")
+load("github.com/SonarSource/cirrus-modules@v3", "load_features")
 
 def main(ctx):
     return load_features(ctx)

.cirrus.yml

@@ -15,7 +15,6 @@ vm_instance_template: &VM_TEMPLATE
   image: docker-builder-v*
   type: t2.small
   region: eu-central-1
-  subnet_id: ${CIRRUS_AWS_SUBNET}
   disk: 10
   cpu: 4
   memory: 16G

Dockerfile

@@ -1,6 +1,6 @@
 FROM sonarsource/sonar-scanner-cli:11.1
 
-LABEL version="3.0.0" \
+LABEL version="3.1.0" \
       repository="https://github.com/sonarsource/sonarqube-scan-action" \
       homepage="https://github.com/sonarsource/sonarqube-scan-action" \
       maintainer="SonarSource" \

entrypoint.sh

@@ -2,6 +2,8 @@
 
 set -eo pipefail
 
+echo "::warning title=Docker removed in the next major version::Users on the master branch of this GitHub action will be upgraded automatically on December 9th to its next major version, which replaces Docker with a composite action, executing in the runner environment. Self-hosted runners analyzing JS/TS code against SonarQube 10.2 and below will need to have Node JS installed."
+
 declare -a args=()
 
 if [[ -z "${SONAR_TOKEN}" ]]; then