Release v0.34.1

What's Changed

• groot/rhist: implement RSlicer for TGraph{,Errors,AsymErrors,MultiErrors} by @sbinet in #996
• all: apply loopvar fixups by @sbinet in #997
• all: bump [email protected], x/{image,net,sync,tools} by @sbinet in #999

Full Changelog: v0.34.0...v0.34.1