serverless/serverless sf-core@4.38.0 on GitHub

Features

Ruby 4.0 runtime support. Functions can now target the ruby4.0 Lambda runtime. (#13613)
```
provider:
  name: aws
  runtime: ruby4.0
```
New ${aws:partition} variable. Resolves to the AWS partition for the deployment region (e.g. aws, aws-cn, aws-us-gov) with no network call or credentials required. Makes ARNs in your configuration portable across commercial, GovCloud, and China partitions. (#12441, #13633)
```
provider:
  iam:
    role:
      managedPolicies:
        - arn:${aws:partition}:iam::aws:policy/AmazonS3ReadOnlyAccess
```
AgentCore: Python 3.14 support. Agent runtimes can now target python3.14. Runtime validation is also stronger, with supported runtimes validated against a single allowlist. (#13645)
```
# AgentCore agent configuration
runtime: python3.14
```

API Gateway custom stage now used for the service endpoint URL and stage tags. When provider.apiGateway.stage is set to a value different from the deployment stage, the ServiceEndpoint output URL and the API Gateway stage tags now use that configured stage. Previously they used the deployment stage, producing an incorrect endpoint URL and attempting to tag a stage that did not exist. (#13636)
```
provider:
  apiGateway:
    stage: customstage   # now reflected in ServiceEndpoint + stage tags
```
Variable resolution no longer drops placeholders during re-entrant resolution. A JavaScript or TypeScript ${file(...)} resolver that calls resolveVariable() or resolveConfigurationProperty() mid-resolution opens a nested resolution pass. Under certain async timing this could leave the outer resolution looking inactive, causing a later nested placeholder to be left unresolved. Each pass now preserves and restores its context so the full dependency chain resolves reliably. (#13635)
AgentCore: unpinned the default Buildpacks builder image and added a builder override. The previously hard-pinned heroku/builder digest is no longer used by default. (#13647, #13646)

Bumped the AWS SDK group with 34 updates (#13632)
Upgraded esbuild to 0.28.1 and tsx to 4.22.4 (#13610, #13644)
Upgraded Go to 1.26.4 and bumped golang.org/x/sys and golang.org/x/mod for the installer (#13618, #13614, #13650)
Upgraded the Jackson libraries (databind, core, annotations, datatype-joda) for the Java runtime wrapper (#13619, #13620, #13621, #13637, #13638, #13639, #13640)
Upgraded graphql to 16.14.0, ajv to 8.20.0, zod to 4.4.3, semver to 7.8.1, hono, @grpc/grpc-js to 1.14.4, and eventsource-parser to 3.1.0 (#13576, #13631, #13577, #13578, #13627, #13630, #13643, #13626)
Patched a uuid buffer-bounds advisory in the bedrock-agentcore examples (#13617)
Bumped grouped npm and GitHub Actions dependencies (#13649, #13648, #13641, #13622, #13624, #13625)