Update CONTRIB_REPO_SHA to opentelemetrybot/prepare-release-1.29.0-0.50b0

Author: xrmx

.github/workflows/contrib.yml

@@ -11,4 +11,4 @@ jobs:
     uses: open-telemetry/opentelemetry-python-contrib/.github/workflows/core_contrib_test_0.yml@main
     with:
       CORE_REPO_SHA: ${{ github.sha }}
-      CONTRIB_REPO_SHA: main
+      CONTRIB_REPO_SHA: opentelemetrybot/prepare-release-1.29.0-0.50b0

.github/workflows/lint_0.yml

@@ -11,7 +11,7 @@ on:
 
 env:
   CORE_REPO_SHA: main
-  CONTRIB_REPO_SHA: main
+  CONTRIB_REPO_SHA: opentelemetrybot/prepare-release-1.29.0-0.50b0
   PIP_EXISTS_ACTION: w
 
 jobs:

.github/workflows/test_0.yml

@@ -11,7 +11,7 @@ on:
 
 env:
   CORE_REPO_SHA: main
-  CONTRIB_REPO_SHA: main
+  CONTRIB_REPO_SHA: opentelemetrybot/prepare-release-1.29.0-0.50b0
   PIP_EXISTS_ACTION: w
 
 jobs:

.github/workflows/test_1.yml

@@ -11,7 +11,7 @@ on:
 
 env:
   CORE_REPO_SHA: main
-  CONTRIB_REPO_SHA: main
+  CONTRIB_REPO_SHA: opentelemetrybot/prepare-release-1.29.0-0.50b0
   PIP_EXISTS_ACTION: w
 
 jobs: