Fix module version for Go package to v5.

[lukehoban]

The version number was still v4 in sdk/go.mod even after this was updated to v5. This made the package unusable from Go.

Also added a test to ensure we test consuming this package from Go.

Fixes #276.
Fixes pulumi/templates#481.

[github-actions]

Does the PR have any schema changes?

Looking good! No breaking changes found.
No new resources/functions.

[guineveresaenger]

During a major version upgrade, we usually disable Go tests - can we merge #284 first, and then add the test by itself?

[github-actions]

Does the PR have any schema changes?

Looking good! No breaking changes found.
No new resources/functions.

[github-actions]

Does the PR have any schema changes?

Found 31 breaking changes:
Resource "github:index/actionsRepositoryPermissions:ActionsRepositoryPermissions" missing
Resource "github:index/branchProtection:BranchProtection" missing input "lockBranch"
Resource "github:index/branchProtection:BranchProtection" missing output "lockBranch"
Resource "github:index/organizationSecurityManager:OrganizationSecurityManager" missing
Resource "github:index/appInstallationRepositories:AppInstallationRepositories" missing
Resource "github:index/release:Release" missing
Resource "github:index/repository:Repository" missing input "securityAndAnalysis"
Resource "github:index/repository:Repository" missing output "securityAndAnalysis"
Resource "github:index/teamSettings:TeamSettings" missing
Function "github:index/getTeam:getTeam" missing input "resultsPerPage"
Function "github:index/getTeam:getTeam" missing input "summaryOnly"
Function "github:index/getTeam:getTeam" missing output "summaryOnly"
Function "github:index/getTeam:getTeam" missing output "resultsPerPage"
Function "github:index/getRepository:getRepository" missing output "template"
Function "github:index/getRepository:getRepository" missing output "isTemplate"
Function "github:index/getRepositories:getRepositories" missing input "includeRepoId"
Function "github:index/getRepositories:getRepositories" missing input "resultsPerPage"
Function "github:index/getRepositories:getRepositories" missing output "repoIds"
Function "github:index/getRepositories:getRepositories" missing output "resultsPerPage"
Function "github:index/getRepositories:getRepositories" missing output "includeRepoId"
Function "github:index/getActionsOrganizationRegistrationToken:getActionsOrganizationRegistrationToken" missing
Function "github:index/getRelease:getRelease" missing output "assetsUrl"
Function "github:index/getActionsRegistrationToken:getActionsRegistrationToken" missing
Type "github:index/RepositorySecurityAndAnalysisAdvancedSecurity:RepositorySecurityAndAnalysisAdvancedSecurity" missing
Type "github:index/BranchProtectionRequiredPullRequestReview:BranchProtectionRequiredPullRequestReview" missing property "requireLastPushApproval"
Type "github:index/getRepositoryTemplate:getRepositoryTemplate" missing
Type "github:index/RepositorySecurityAndAnalysisSecretScanning:RepositorySecurityAndAnalysisSecretScanning" missing
Type "github:index/ActionsRepositoryPermissionsAllowedActionsConfig:ActionsRepositoryPermissionsAllowedActionsConfig" missing
Type "github:index/TeamSettingsReviewRequestDelegation:TeamSettingsReviewRequestDelegation" missing
Type "github:index/RepositorySecurityAndAnalysisSecretScanningPushProtection:RepositorySecurityAndAnalysisSecretScanningPushProtection" missing
Type "github:index/RepositorySecurityAndAnalysis:RepositorySecurityAndAnalysis" missing
No new resources/functions.

[lukehoban]

Superseded by #284.