switch data volumes to SSD type gp2

Test: sudo hdparm -tT /dev/nvme1n1
Before:

/dev/nvme1n1:
 Timing cached reads:   9642 MB in  2.00 seconds = 4825.42 MB/sec
 Timing buffered disk reads:  54 MB in  3.94 seconds =  13.71 MB/sec

After:

/dev/nvme1n1:
 Timing cached reads:   12028 MB in  2.00 seconds = 6020.63 MB/sec
 Timing buffered disk reads: 512 MB in  3.01 seconds = 170.08 MB/sec

Signed-off-by: Jakub Sokołowski <jakub@status.im>

nimbus.tf

@@ -33,6 +33,7 @@ module "nimbus_master" {
   instance_type = "t3a.medium"
   root_vol_size = 20
   data_vol_size = 150
+  data_vol_type = "gp2"
   host_count    = 1
 
   /* Firewall */
@@ -58,6 +59,7 @@ module "nimbus_nodes" {
   instance_type = "t3a.medium"
   root_vol_size = 20
   data_vol_size = 150
+  data_vol_type = "gp2"
   host_count    = var.hosts_count
 
   /* Firewall */