feat: Add run_attempt to workflow_runs schema (#283)

**Summary**
This pull request adds the `run_attempt` property to the workflow_runs
schema. This will give the ability to filter out
re-runs(`run_attempt>1`) in the workflow runs metrics.

**Changes**
Updated `repository_streams.py` to include `run_attempt` in the schema
definition of the workflow_runs stream.

**Testing**
1. Confirmed that Github REST API endpoint for workflow runs response
returns `run_attempt` field in the response.
2. Tested the changes locally using Meltano to ensure the `run_attempt`
field is correctly included in response and populated in the target.

tap_github/repository_streams.py

@@ -1975,6 +1975,7 @@ class WorkflowRunsStream(GitHubRestStream):
         th.Property("head_branch", th.StringType),
         th.Property("head_sha", th.StringType),
         th.Property("run_number", th.IntegerType),
+        th.Property("run_attempt", th.IntegerType),
         th.Property("event", th.StringType),
         th.Property("status", th.StringType),
         th.Property("conclusion", th.StringType),