Pin speculos version

Author: Fingolfin69

tests/standalone/requirements.txt

@@ -1,5 +1,9 @@
 pytest
 ragger[speculos,ledgerwallet]>=1.21.1
+# Pin Speculos: newer/older resolutions crash rendering the Stax home screen at
+# api_level 26 (hal_draw_image_file IndexError on empty image data). 0.26.8 is
+# the version the whole standalone suite passes against on all devices.
+speculos==0.26.8
 ecdsa>=0.16.1,<0.17.0
 safe-pysha3>=1.0.0,<2.0.0
 tomli>=2.0.1