Fix jupyterquiz at 2.6.3 as otherwise it doesn't recognize <br />.

content/forces.md

@@ -533,6 +533,7 @@ t-t_0 = \int_{x_0}^x \frac{1}{v(x')} \mathrm{d}x',
 $$ (implicitposition)
 
 which gives us $t(x)$. In principle we can invert this expression to give us $x(t)$, although in practice this may not be easy. 
+
 ### Case 3: $F = F(v)$
 If the force depends only on the velocity, there are two ways we can proceed. We can write the equation of motion as $m \mathrm{d}v / \mathrm{d} t = F(v)$ and use separation of variables to get:
 

content/quizes/chapter3/c3q3.json

 [
      {
-         "question": "An 80-ton airplane stands on the tarmac. The airplane is 50 meters long; the main wheels are 27 meters from the nose, and the nose wheel is 3 meters from the nose. How large is the force on the nose wheel?<br />(We assume the mass of the plane is distributed uniformly.)",
+         "question": "An 80-ton airplane stands on the tarmac. The airplane is 50 meters long; the main wheels are 27 meters from the nose, and the nose wheel is 3 meters from the nose. How large is the force on the nose wheel?<br /> (We assume the mass of the plane is distributed uniformly.)",
          "type": "multiple_choice",
          "answers": [
              {

requirements.txt

@@ -6,5 +6,5 @@ matplotlib
 myst_nb
 sphinx-exercise
 sphinx-proof
-jupyterquiz
+jupyterquiz==2.6.3
 pydata-sphinx-theme