fixed a trailing comma in json file

plotting/roofline_data.json

@@ -29,13 +29,13 @@
     "icx32":{
         "hostname": "icx32",
         "date": "Thu 03 Aug 2023 09:31:24 AM CEST",
-        "perf":{
+        "perf": {
             "peakflops":             341026.79,
             "peakflops_sse":         835759.60
             "peakflops_avx":        1665387.70,
             "peakflops_avx512":     2929571.20,
             "peakflops_avx512_fma": 5863109.89,
-            "peakflops_avx_fma":    3331900.48,
+            "peakflops_avx_fma":    3331900.48
         },
         "bw":{
             "load":                 351975.45
@@ -48,7 +48,7 @@
         "perf": {
             "peakflops":             318008.12,
             "peakflops_avx":        1131510.50,
-            "peakflops_avx_fma":   1326727.67,
+            "peakflops_avx_fma":    1326727.67,
             "peakflops_sse":         617396.67
         },
         "bw": {