Fix code style issues in gravity notebooks

Author: santisoler

notebooks/03-gravity/fwd_gravity_anomaly_3d.ipynb

@@ -76,6 +76,8 @@
    },
    "outputs": [],
    "source": [
+    "import os\n",
+    "\n",
     "# SimPEG functionality\n",
     "from simpeg.potential_fields import gravity\n",
     "from simpeg.utils import plot2Ddata, model_builder\n",
@@ -89,11 +91,9 @@
     "import numpy as np\n",
     "from scipy.interpolate import LinearNDInterpolator\n",
     "import matplotlib as mpl\n",
-    "\n",
-    "mpl.rcParams.update({\"font.size\": 14})\n",
     "import matplotlib.pyplot as plt\n",
-    "import os\n",
     "\n",
+    "mpl.rcParams.update({\"font.size\": 14})\n",
     "save_output = False  # Optional"
    ]
   },

notebooks/03-gravity/fwd_gravity_gradiometry_3d.ipynb

@@ -92,10 +92,9 @@
     "import numpy as np\n",
     "from scipy.interpolate import LinearNDInterpolator\n",
     "import matplotlib as mpl\n",
-    "\n",
-    "mpl.rcParams.update({\"font.size\": 14})\n",
     "import matplotlib.pyplot as plt\n",
     "\n",
+    "mpl.rcParams.update({\"font.size\": 14})\n",
     "save_output = False  # Optional"
    ]
   },