fix types of some github context properties

Author: rhysd

docs/checks.md

@@ -404,7 +404,7 @@ test.yaml:7:24: undefined variable "unknown_context". available variables are "e
   |
 7 |       - run: echo '${{ unknown_context }}'
   |                        ^~~~~~~~~~~~~~~
-test.yaml:9:24: property "events" is not defined in object type {action: string; action_path: string; action_ref: string; action_repository: string; action_status: string; actor: string; actor_id: string; api_url: string; artifact_cache_size_limit: string; base_ref: string; env: string; event: object; event_name: string; event_path: string; graphql_url: string; head_ref: string; job: string; output: string; path: string; ref: string; ref_name: string; ref_protected: string; ref_type: string; repository: string; repository_id: string; repository_owner: string; repository_owner_id: string; repository_visibility: string; repositoryurl: string; retention_days: number; run_attempt: string; run_id: string; run_number: string; secret_source: string; server_url: string; sha: string; state: string; step_summary: string; token: string; triggering_actor: string; workflow: string; workflow_ref: string; workflow_sha: string; workspace: string} [expression]
+test.yaml:9:24: property "events" is not defined in object type {action: string; action_path: string; action_ref: string; action_repository: string; action_status: string; actor: string; actor_id: string; api_url: string; artifact_cache_size_limit: number; base_ref: string; env: string; event: object; event_name: string; event_path: string; graphql_url: string; head_ref: string; job: string; output: string; path: string; ref: string; ref_name: string; ref_protected: bool; ref_type: string; repository: string; repository_id: string; repository_owner: string; repository_owner_id: string; repository_visibility: string; repositoryurl: string; retention_days: number; run_attempt: string; run_id: string; run_number: string; secret_source: string; server_url: string; sha: string; state: string; step_summary: string; token: string; triggering_actor: string; workflow: string; workflow_ref: string; workflow_sha: string; workspace: string} [expression]
   |
 9 |       - run: echo '${{ github.events }}'
   |                        ^~~~~~~~~~~~~

expr_sema.go

@@ -211,7 +211,7 @@ var BuiltinGlobalVariableTypes = map[string]ExprType{
 		"actor":                     StringType{},
 		"actor_id":                  StringType{},
 		"api_url":                   StringType{},
-		"artifact_cache_size_limit": StringType{}, // Note: Undocumented
+		"artifact_cache_size_limit": NumberType{}, // Note: Undocumented
 		"base_ref":                  StringType{},
 		"env":                       StringType{},
 		"event":                     NewEmptyObjectType(), // Note: Stricter type check for this payload would be possible
@@ -224,7 +224,7 @@ var BuiltinGlobalVariableTypes = map[string]ExprType{
 		"path":                      StringType{},
 		"ref":                       StringType{},
 		"ref_name":                  StringType{},
-		"ref_protected":             StringType{},
+		"ref_protected":             BoolType{},
 		"ref_type":                  StringType{},
 		"repository":                StringType{},
 		"repository_id":             StringType{},