exa docs and python package update (#31307)

Added support for new Exa API features. Updated Exa docs and python
package (langchain-exa).

Description

Added support for new Exa API features in the langchain-exa package:
- Added max_characters option for text content
- Added support for summary and custom summary prompts
- Added livecrawl option with "always", "fallback", "never" settings
- Added "auto" option for search type
- Updated documentation and tests

Dependencies
- No new dependencies required. Using existing features from exa-py.

twitter: @theishangoswami

---------

Co-authored-by: Chester Curme <chester.curme@gmail.com>

libs/partners/exa/uv.lock

@@ -1,5 +1,4 @@
 version = 1
-revision = 1
 requires-python = ">=3.9"
 resolution-markers = [
     "python_full_version >= '3.13'",
@@ -394,7 +393,7 @@ wheels = [
 
 [[package]]
 name = "langchain-core"
-version = "0.3.56"
+version = "0.3.60"
 source = { editable = "../../core" }
 dependencies = [
     { name = "jsonpatch" },
@@ -409,10 +408,9 @@ dependencies = [
 [package.metadata]
 requires-dist = [
     { name = "jsonpatch", specifier = ">=1.33,<2.0" },
-    { name = "langsmith", specifier = ">=0.1.125,<0.4" },
+    { name = "langsmith", specifier = ">=0.1.126,<0.4" },
     { name = "packaging", specifier = ">=23.2,<25" },
-    { name = "pydantic", marker = "python_full_version < '3.12.4'", specifier = ">=2.5.2,<3.0.0" },
-    { name = "pydantic", marker = "python_full_version >= '3.12.4'", specifier = ">=2.7.4,<3.0.0" },
+    { name = "pydantic", specifier = ">=2.7.4" },
     { name = "pyyaml", specifier = ">=5.3" },
     { name = "tenacity", specifier = ">=8.1.0,!=8.4.0,<10.0.0" },
     { name = "typing-extensions", specifier = ">=4.7" },
@@ -453,7 +451,7 @@ typing = [
 
 [[package]]
 name = "langchain-exa"
-version = "0.2.1"
+version = "0.3.0"
 source = { editable = "." }
 dependencies = [
     { name = "exa-py" },