Fix lint errors reported by revive

The revive is almost the same as golint, but there seems to be a bit
different results.

https://app.circleci.com/pipelines/github/runatlantis/atlantis/1519/workflows/75fd7da5-1532-4ed7-ac8a-4884902818a4/jobs/8314
https://github.com/runatlantis/atlantis/pull/1801/checks?check_run_id=3565887247

server/core/locking/locking_test.go

@@ -178,7 +178,7 @@ func TestGetLock_NoOpLocker(t *testing.T) {
 	l := locking.NewNoOpLocker()
 	lock, err := l.GetLock("owner/repo/path/workspace")
 	Ok(t, err)
-	var expected *models.ProjectLock = nil
+	var expected *models.ProjectLock
 	Equals(t, expected, lock)
 }
 

server/core/runtime/policy/conftest_client.go

@@ -94,7 +94,7 @@ func (p *SourceResolverProxy) Resolve(policySet valid.PolicySet) (string, error)
 	case valid.LocalPolicySet:
 		return p.localSourceResolver.Resolve(policySet)
 	default:
-		return "", errors.New(fmt.Sprintf("unable to resolve policy set source %s", source))
+		return "", fmt.Errorf("unable to resolve policy set source %s", source)
 	}
 }
 
@@ -237,7 +237,7 @@ func getDefaultVersion() (*version.Version, error) {
 	defaultVersion, exists := os.LookupEnv(DefaultConftestVersionEnvKey)
 
 	if !exists {
-		return nil, errors.New(fmt.Sprintf("%s not set.", DefaultConftestVersionEnvKey))
+		return nil, fmt.Errorf("%s not set", DefaultConftestVersionEnvKey)
 	}
 
 	wrappedVersion, err := version.NewVersion(defaultVersion)

server/events/pre_workflow_hooks_command_runner_test.go

@@ -74,7 +74,7 @@ func TestRunPreHooks_Clone(t *testing.T) {
 	t.Run("success hooks in cfg", func(t *testing.T) {
 		preWorkflowHooksSetup(t)
 
-		var unlockCalled *bool = newBool(false)
+		var unlockCalled = newBool(false)
 		unlockFn := func() {
 			unlockCalled = newBool(true)
 		}
@@ -159,7 +159,7 @@ func TestRunPreHooks_Clone(t *testing.T) {
 	t.Run("error cloning", func(t *testing.T) {
 		preWorkflowHooksSetup(t)
 
-		var unlockCalled *bool = newBool(false)
+		var unlockCalled = newBool(false)
 		unlockFn := func() {
 			unlockCalled = newBool(true)
 		}
@@ -191,7 +191,7 @@ func TestRunPreHooks_Clone(t *testing.T) {
 	t.Run("error running pre hook", func(t *testing.T) {
 		preWorkflowHooksSetup(t)
 
-		var unlockCalled *bool = newBool(false)
+		var unlockCalled = newBool(false)
 		unlockFn := func() {
 			unlockCalled = newBool(true)
 		}

server/events/yaml/valid/global_cfg.go

@@ -27,7 +27,7 @@ const DeleteSourceBranchOnMergeKey = "delete_source_branch_on_merge"
 // TODO: Make this more customizable, not everyone wants this rigid workflow
 // maybe something along the lines of defining overridable/non-overrideable apply
 // requirements in the config and removing the flag to enable policy checking.
-var NonOverrideableApplyReqs []string = []string{PoliciesPassedApplyReq}
+var NonOverrideableApplyReqs = []string{PoliciesPassedApplyReq}
 
 // GlobalCfg is the final parsed version of server-side repo config.
 type GlobalCfg struct {