chore: add constraints file check for python samples (#170)

This is the sibling PR to https://github.com/GoogleCloudPlatform/python-docs-samples/pull/5611
and this is the issue opened for it https://github.com/GoogleCloudPlatform/python-docs-samples/issues/5549
diff --git a/.github/header-checker-lint.yml b/.github/header-checker-lint.yml
index fc281c0..6fe78aa 100644
--- a/.github/header-checker-lint.yml
+++ b/.github/header-checker-lint.yml
@@ -1,6 +1,6 @@
 {"allowedCopyrightHolders": ["Google LLC"],
  "allowedLicenses": ["Apache-2.0", "MIT", "BSD-3"],
- "ignoreFiles": ["**/requirements.txt", "**/requirements-test.txt"],
+ "ignoreFiles": ["**/requirements.txt", "**/requirements-test.txt", "**/__init__.py", "samples/**/constraints.txt", "samples/**/constraints-test.txt"],
  "sourceFileExtensions": [
  	"ts", 
  	"js", 
diff --git a/renovate.json b/renovate.json
index f08bc22..c048955 100644
--- a/renovate.json
+++ b/renovate.json
@@ -2,5 +2,8 @@
   "extends": [
     "config:base",  ":preserveSemverRanges"
   ],
-  "ignorePaths": [".pre-commit-config.yaml"]
+  "ignorePaths": [".pre-commit-config.yaml"],
+  "pip_requirements": {
+    "fileMatch": ["requirements-test.txt", "samples/[\\S/]*constraints.txt", "samples/[\\S/]*constraints-test.txt"]
+  }
 }
diff --git a/synth.metadata b/synth.metadata
index c66286d..24df57c 100644
--- a/synth.metadata
+++ b/synth.metadata
@@ -4,14 +4,14 @@
       "git": {
         "name": ".",
         "remote": "https://github.com/googleapis/python-api-core.git",
-        "sha": "49c6755a21215bbb457b60db91bab098185b77da"
+        "sha": "8c7ac29ce8b1680fc0991f5001ed4a6ad580f951"
       }
     },
     {
       "git": {
         "name": "synthtool",
         "remote": "https://github.com/googleapis/synthtool.git",
-        "sha": "5b5bf6d519b2d658d9f2e483d9f6f3d0ba8ee6bc"
+        "sha": "0a071b3460344886297a304253bf924aa68ddb7e"
       }
     }
   ],