gallery example "Blockmean": Remove un-needed square brackets (#2724)

Remove un-needed square brackets

Author: yvonnefroehlich

examples/gallery/histograms/blockm.py

@@ -39,7 +39,7 @@
 fig.coast(land="darkgray", transparency=40)
 # Plot original data points
 fig.plot(x=data.longitude, y=data.latitude, style="c0.3c", fill="white", pen="1p,black")
-fig.colorbar(frame=["x+lkm"])
+fig.colorbar(frame="x+lkm")
 
 fig.shift_origin(xshift="w+5c")
 
@@ -56,6 +56,6 @@
 )
 fig.coast(land="darkgray", transparency=40)
 fig.plot(x=data.longitude, y=data.latitude, style="c0.3c", fill="white", pen="1p,black")
-fig.colorbar(frame=["x+lcount"])
+fig.colorbar(frame="x+lcount")
 
 fig.show()