🐛 Fix PTC/BTC whole number tests (#22255)

Marlin/src/inc/SanityCheck.h

@@ -593,24 +593,29 @@ static_assert(COUNT(arm) == LOGICAL_AXES, "AXIS_RELATIVE_MODES must contain " _L
   #endif
 
   #ifdef PTC_SAMPLE_START
-    constexpr int _ptc_sample_start = PTC_SAMPLE_START;
-    static_assert(_test_ptc_sample_start != PTC_SAMPLE_START, "PTC_SAMPLE_START must be a whole number.");
+    constexpr auto _ptc_sample_start = PTC_SAMPLE_START;
+    constexpr decltype(_ptc_sample_start) _test_ptc_sample_start = 12.3f;
+    static_assert(_test_ptc_sample_start != 12.3f, "PTC_SAMPLE_START must be a whole number.");
   #endif
   #ifdef PTC_SAMPLE_RES
-    constexpr int _ptc_sample_res = PTC_SAMPLE_END;
-    static_assert(_test_ptc_sample_res != PTC_SAMPLE_END, "PTC_SAMPLE_RES must be a whole number.");
+    constexpr auto _ptc_sample_res = PTC_SAMPLE_RES;
+    constexpr decltype(_ptc_sample_res) _test_ptc_sample_res = 12.3f;
+    static_assert(_test_ptc_sample_res != 12.3f, "PTC_SAMPLE_RES must be a whole number.");
   #endif
   #ifdef BTC_SAMPLE_START
-    constexpr int _btc_sample_start = BTC_SAMPLE_START;
-    static_assert(_test_btc_sample_start != BTC_SAMPLE_START, "BTC_SAMPLE_START must be a whole number.");
+    constexpr auto _btc_sample_start = BTC_SAMPLE_START;
+    constexpr decltype(_btc_sample_start) _test_btc_sample_start = 12.3f;
+    static_assert(_test_btc_sample_start != 12.3f, "BTC_SAMPLE_START must be a whole number.");
   #endif
   #ifdef BTC_SAMPLE_RES
-    constexpr int _btc_sample_res = BTC_SAMPLE_END;
-    static_assert(_test_btc_sample_res != BTC_SAMPLE_END, "BTC_SAMPLE_RES must be a whole number.");
+    constexpr _btc_sample_res = BTC_SAMPLE_RES;
+    constexpr decltype(_btc_sample_res) _test_btc_sample_res = 12.3f;
+    static_assert(_test_btc_sample_res != 12.3f, "BTC_SAMPLE_RES must be a whole number.");
   #endif
   #ifdef BTC_PROBE_TEMP
-    constexpr int _btc_probe_temp = BTC_PROBE_TEMP;
-    static_assert(_test_btc_probe_temp != BTC_PROBE_TEMP, "BTC_PROBE_TEMP must be a whole number.");
+    constexpr auto _btc_probe_temp = BTC_PROBE_TEMP;
+    constexpr decltype(_btc_probe_temp) _test_btc_probe_temp = 12.3f;
+    static_assert(_test_btc_probe_temp != 12.3f, "BTC_PROBE_TEMP must be a whole number.");
   #endif
 #endif