WASHINGTON – Lawmakers probing the 2021 attack on the US Capitol subpoenaed former president Donald Trump Friday to testify on his involvement in the violence, in a major escalation of its sprawling inquiry. The summons came after the House panel of seven Democrats and two Republicans voted unanimously last week to compel Trump’s appearance before investigators. It requires Trump to produce documents to the committee by November 4 and to appear for a deposition beginning on or around November 14 — the Monday after the crucial November 8 midterm elections. “As demonstrated in our hearings, we h…