Many languages distinguish between inclusive and exclusive first-person plural pronouns (“we”). (Click or tap here to see more details)
The inclusive “we” specifically includes the addressee (“you and I and possibly others”), while the exclusive “we” specifically excludes the addressee (“he/she/they and I, but not you”). This grammatical distinction is called “clusivity.” While Semitic languages such as Hebrew or most Indo-European languages such as Greek or English do not make that distinction, translators of languages with that distinction have to make a choice every time they encounter “we” or a form thereof (in English: “we,” “our,” or “us”).
According to Velma Pickett and Florence Cowan (in Notes on Translation January 1962, p. 1ff.) translators typically select the exclusive form (excluding Paul) for this verse. According to SIL International Translation Department (1999) it is also possible to use the inclusive form which would include Paul.