chore(lint): add new linters and update codebase

- add canonicalheader
- add copyloopvar
- add fatcontext
- add intrange

internal/configuration/settings/firewall.go

@@ -104,7 +104,6 @@ func (f Firewall) toLinesNode() (node *gotree.Node) {
 	if len(f.OutboundSubnets) > 0 {
 		outboundSubnets := node.Appendf("Outbound subnets:")
 		for _, subnet := range f.OutboundSubnets {
-			subnet := subnet
 			outboundSubnets.Appendf("%s", &subnet)
 		}
 	}

internal/configuration/settings/firewall_test.go

@@ -59,7 +59,6 @@ func Test_Firewall_validate(t *testing.T) {
 	}
 
 	for name, testCase := range testCases {
-		testCase := testCase
 		t.Run(name, func(t *testing.T) {
 			t.Parallel()
 

internal/configuration/settings/openvpn_test.go

@@ -32,7 +32,6 @@ func Test_ivpnAccountID(t *testing.T) {
 	}
 
 	for _, testCase := range testCases {
-		testCase := testCase
 		t.Run(testCase.s, func(t *testing.T) {
 			t.Parallel()
 

internal/configuration/settings/settings_test.go

@@ -86,7 +86,6 @@ func Test_Settings_String(t *testing.T) {
 	}
 
 	for name, testCase := range testCases {
-		testCase := testCase
 		t.Run(name, func(t *testing.T) {
 			t.Parallel()
 

internal/configuration/sources/files/wireguard_test.go

@@ -73,7 +73,6 @@ PresharedKey = YJ680VN+dGrdsWNjSFqZ6vvwuiNhbq502ZL3G7Q3o3g=
 	}
 
 	for testName, testCase := range testCases {
-		testCase := testCase
 		t.Run(testName, func(t *testing.T) {
 			t.Parallel()
 
@@ -123,7 +122,6 @@ Address = 10.38.22.35/32
 	}
 
 	for testName, testCase := range testCases {
-		testCase := testCase
 		t.Run(testName, func(t *testing.T) {
 			t.Parallel()
 
@@ -184,7 +182,6 @@ Endpoint = 1.2.3.4:51820`,
 	}
 
 	for testName, testCase := range testCases {
-		testCase := testCase
 		t.Run(testName, func(t *testing.T) {
 			t.Parallel()
 

internal/configuration/sources/secrets/reader_test.go

@@ -91,7 +91,6 @@ func Test_Source_Get(t *testing.T) {
 	}
 
 	for name, testCase := range testCases {
-		testCase := testCase
 		t.Run(name, func(t *testing.T) {
 			t.Parallel()