testautomation keyboard: use `space` instead of `a`

(cherry picked from commit 1ed1bc1d5da2c5e0a9a223411d39f3d3c4a5a9fd)

test/testautomation_keyboard.c

@@ -127,9 +127,9 @@ int keyboard_getKeyFromScancode(void *arg)
     SDL_Keycode result;
 
     /* Case where input is valid */
-    result = SDL_GetKeyFromScancode(SDL_SCANCODE_A);
+    result = SDL_GetKeyFromScancode(SDL_SCANCODE_SPACE);
     SDLTest_AssertPass("Call to SDL_GetKeyFromScancode(valid)");
-    SDLTest_AssertCheck(result == SDLK_a, "Verify result from call, expected: %i, got: %" SDL_PRIs32, SDLK_a, result);
+    SDLTest_AssertCheck(result == SDLK_SPACE, "Verify result from call, expected: %i, got: %" SDL_PRIs32, SDLK_SPACE, result);
 
     /* Case where input is zero */
     result = SDL_GetKeyFromScancode(0);