Remove v0.2 of SLSA as no longer supported

Author: Romuald Atchadé

Diff for: PROVENANCE.md

@@ -1,8 +1,9 @@
 # GitLab CI provenance
+
 When enabled with variable **RUNNER_GENERATE_ARTIFACTS_METADATA**, runner produces [SLSA provenance v0.2](https://slsa.dev/spec/v0.2/provenance) statements.
 
 You can configure the runner by setting the variable **SLSA_PROVENANCE_SCHEMA_VERSION**.
 
-The supported schemas versions are:
-* [v0.2](https://slsa.dev/spec/v0.2/provenance)
-* [v1](https://slsa.dev/spec/v1/provenance)
+The supported schema version is:
+
+- [v1](https://slsa.dev/spec/v1/provenance)