Add linter checks to GHA & Fix code to pass lints

Add linter checks to GHA & Fix code to pass lints.
The linters added are:
- whitespace: Tool for detection of leading and trailing whitespace
- gosec: Inspects source code for security problems
- gci: Gci control golang package import order and make it always deterministic
- misspell: Finds commonly misspelled English words in comments
- gomnd: An analyzer to detect magic numbers

The file utils/utils.go is excluded from the checks of gomnd, as uses magic numbers through the code

priceupdater/priceupdater_test.go

@@ -7,7 +7,6 @@ import (
 )
 
 func TestCon(t *testing.T) {
-
 	config := ConfigPriceUpdater{
 
 		RecommendedFee:              1,
@@ -36,5 +35,4 @@ func TestCon(t *testing.T) {
 	prices := pud.GetPrices()
 	assert.Equal(t, prices["ETH"], info)
 	assert.Equal(t, prices["NEC"], info2)
-
 }