Update elasticsearch requirement from ~> 8.2.0 to ~> 8.15.0

Updates the requirements on [elasticsearch](https://github.com/elastic/elasticsearch-ruby) to permit the latest version.
- [Release notes](https://github.com/elastic/elasticsearch-ruby/releases)
- [Changelog](https://github.com/elastic/elasticsearch-ruby/blob/main/CHANGELOG.md)
- [Commits](elastic/elasticsearch-ruby@v8.2.2...v8.15.0)

---
updated-dependencies:
- dependency-name: elasticsearch
  dependency-type: direct:development
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

Gemfile.lock

@@ -129,13 +129,13 @@ GEM
       dry-initializer (~> 3.0)
       dry-schema (>= 1.12, < 2)
       zeitwerk (~> 2.6)
-    elastic-transport (8.3.2)
+    elastic-transport (8.3.5)
       faraday (< 3)
       multi_json
-    elasticsearch (8.2.2)
-      elastic-transport (~> 8.0)
-      elasticsearch-api (= 8.2.2)
-    elasticsearch-api (8.2.2)
+    elasticsearch (8.15.0)
+      elastic-transport (~> 8.3)
+      elasticsearch-api (= 8.15.0)
+    elasticsearch-api (8.15.0)
       multi_json
     epsilla-ruby (0.0.4)
       faraday (>= 1)
@@ -452,7 +452,7 @@ DEPENDENCIES
   cohere-ruby (~> 0.9.10)
   docx (~> 0.8.0)
   dotenv-rails (~> 2.7.6)
-  elasticsearch (~> 8.2.0)
+  elasticsearch (~> 8.15.0)
   epsilla-ruby (~> 0.0.4)
   eqn (~> 1.6.5)
   faraday

langchain.gemspec

@@ -48,7 +48,7 @@ Gem::Specification.new do |spec|
   spec.add_development_dependency "chroma-db", "~> 0.6.0"
   spec.add_development_dependency "cohere-ruby", "~> 0.9.10"
   spec.add_development_dependency "docx", "~> 0.8.0"
-  spec.add_development_dependency "elasticsearch", "~> 8.2.0"
+  spec.add_development_dependency "elasticsearch", "~> 8.15.0"
   spec.add_development_dependency "epsilla-ruby", "~> 0.0.4"
   spec.add_development_dependency "eqn", "~> 1.6.5"
   spec.add_development_dependency "faraday"