swap exec for execFile in fetchGitData

Credit: Adar Zandberg from the CxSCA AppSec team at Checkmarx.

* devDependency updates from Dependabot alerts
* bump version

3.1.0

3.0.14

remove redundant code (#283)

The check is already done above.

3.0.12

added COVERALLS_SERVICE_NUMBER to Readme; ver bump

bump version