Starbucks Corp. has upgraded its paid parental leave plan for U.S. employees to at least 12 weeks of unpaid leave and as much as 18 weeks of fully paid leave. The move comes after Starbucks made other investments in its employees in 2016. Considered a tech company by many, Starbucks is expanding benefits after Microsoft, Amazon and other tech companies changed family leave policies amid intense competition to attract and retain employees. Some of the changes Starbucks (Nasdaq: SBUX) made last year…