fix(mcu-tests): strip stray literal backslash-r in Makefile continuations

The previous commit accidentally introduced the literal 2-byte sequence
'\r' at the end of two backslash-continuation lines (TESTS_STANDALONE
and the .PHONY list). GNU make on Linux treats that as text rather than
a line continuation, which orphans the following line with leading
spaces and aborts CI with:

  Makefile:68: *** missing separator (did you mean TAB instead of 8 spaces?)

Strip the extraneous 'r' so each continuation ends with a real backslash
+ LF.

9_Firmware/9_1_Microcontroller/tests/Makefile

@@ -64,7 +64,7 @@ TESTS_STANDALONE := test_bug12_pa_cal_loop_inverted \
                     test_gap3_iwdg_config \
                     test_gap3_temperature_max \
                     test_gap3_idq_periodic_reread \
-                    test_gap3_emergency_state_ordering \r
+                    test_gap3_emergency_state_ordering \
                     test_gap3_overtemp_emergency_stop
 
 # Tests that need platform_noos_stm32.o + mocks
@@ -77,7 +77,7 @@ ALL_TESTS := $(TESTS_WITH_REAL) $(TESTS_MOCK_ONLY) $(TESTS_STANDALONE) $(TESTS_W
 
 .PHONY: all build test clean \
         $(addprefix test_,bug1 bug2 bug3 bug4 bug5 bug6 bug7 bug8 bug9 bug10 bug11 bug12 bug13 bug14 bug15) \
-        test_gap3_estop test_gap3_iwdg test_gap3_temp test_gap3_idq test_gap3_order \r
+        test_gap3_estop test_gap3_iwdg test_gap3_temp test_gap3_idq test_gap3_order \
         test_gap3_overtemp
 
 all: build test