A connection I made asked me to come in for an JOB interview, but I have school+an internship. Help?

Long story short, I made connections during my Fall internship--it ended in November. Flashforward to today and I get an email from the recruiting team that a Job...a job is available and that someone a talked to forwarded my resume to recruitment and that they want me to come into interview for a position that is available.

I can't, however, because this is my last semester in University and I need to work on my thesis AND I already accepted another internship at a different company for the semester.

How do I word my response back so that they keep me in their thoughts for any future positions that they may have in the future? I don't want to burn any bridges. I talked to a lot of people in the company during my time there and made connections. Should I email both the recruiter and the connection I made, thanking them for thinking of me mentioning that I graduate in June and that I'd be available then?

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