UNION * Fails to resolve subsequent column lineage in UNION clause

[skada-coder]

Describe the bug
When parsing a UNION clause using * and the MetadataProvider class it fails to resolve subsequent source columns in the UNION clause.

Below is a simplified example.

SQL
Paste the SQL text here. For example:

CREATE TABLE MAIN.FOOBAR AS (
    SELECT * FROM MAIN.BAR
    UNION
    SELECT * FROM MAIN.BAR2
    UNION
    SELECT * FROM MAIN.BAR3
)

Column Lineage fails to resolve columns from MAIN.BAR2 and MAIN.BAR3 but MAIN.BAR is fine

To Reproduce

from sqllineage.core.metadata.dummy import DummyMetaDataProvider
from sqllineage.runner import LineageRunner
metadata = {
    "main.bar": ["col1", "col2"],
    "main.bar2": ["col1", "col2"],
    "main.bar3": ["col1", "col2"]
}
provider = DummyMetaDataProvider(metadata)
sql1 = """
CREATE TABLE MAIN.FOOBAR AS (
    SELECT * FROM MAIN.BAR
    UNION
    SELECT * FROM MAIN.BAR2
    UNION
    SELECT * FROM MAIN.BAR3
)
"""
LineageRunner(sql1, metadata_provider=provider).print_column_lineage()

actual output is

main.foobar.col1 <- main.bar.col1
main.foobar.col2 <- main.bar.col2

I'd expect it to return this instead

main.foobar.col1 <- main.bar.col1
main.foobar.col2 <- main.bar.col2
main.foobar.col1 <- main.bar2.col1
main.foobar.col2 <- main.bar2.col2
main.foobar.col1 <- main.bar3.col1
main.foobar.col2 <- main.bar3.col2

Python version (available via python --version)

• 3.11.5

SQLLineage version (available via sqllineage --version):

• 1.5.3

Note that this issue does not occur in the non * case where the columns are all explicit in the UNION clause so looks like it only impacts * scenario.

We noticed the issue using the snowflake dialect for our own production use cases