That's the subjunctive mood.

From the link:

The subjunctive in Modern English is easily distinguished in a variety of contexts in which the present subjunctive is used where the sense is past tense. Regardless of the subject, the form of the present subjunctive verb is the infinitive unpreceded by "to". Hence, the subjunctive of "to go" is "I go", "you go", "he/she/it go", "we go", "they go". For instance: "It was required that we go to the back of the line."