Fix golangci-lint config and upgrade actions

- Use golangci-lint v1 config format (compatible with v1.64.8)
- Upgrade actions/setup-go from v5 to v6
- Upgrade codecov/codecov-action from v4 to v5

Author: cv

.github/workflows/ci.yml

@@ -13,7 +13,7 @@ jobs:
       - uses: actions/checkout@v6
 
       - name: Set up Go
-        uses: actions/setup-go@v5
+        uses: actions/setup-go@v6
         with:
           go-version-file: go.mod
 
@@ -24,7 +24,7 @@ jobs:
         run: go test -v -race -coverprofile=coverage.out ./...
 
       - name: Upload coverage
-        uses: codecov/codecov-action@v4
+        uses: codecov/codecov-action@v5
         with:
           files: coverage.out
         continue-on-error: true
@@ -35,7 +35,7 @@ jobs:
       - uses: actions/checkout@v6
 
       - name: Set up Go
-        uses: actions/setup-go@v5
+        uses: actions/setup-go@v6
         with:
           go-version-file: go.mod
 
@@ -54,7 +54,7 @@ jobs:
       - uses: actions/checkout@v6
 
       - name: Set up Go
-        uses: actions/setup-go@v5
+        uses: actions/setup-go@v6
         with:
           go-version-file: go.mod
 

.github/workflows/release.yml

@@ -17,7 +17,7 @@ jobs:
           fetch-depth: 0
 
       - name: Set up Go
-        uses: actions/setup-go@v5
+        uses: actions/setup-go@v6
         with:
           go-version-file: go.mod
 

.golangci.yml

@@ -1,5 +1,3 @@
-version: "2"
-
 run:
   timeout: 5m
 
@@ -14,25 +12,22 @@ linters:
     - unconvert
     - unparam
     - gocritic
-  
-  exclusions:
-    rules:
-      - path: _test\.go
-        linters:
-          - unparam
-      # IATA codes are not misspellings
-      - path: codes/iata\.go
-        linters:
-          - misspell
-
-  settings:
-    gocritic:
-      enabled-tags:
-        - diagnostic
-        - style
-        - performance
-
-formatters:
-  enable:
     - gofmt
     - goimports
+
+linters-settings:
+  gocritic:
+    enabled-tags:
+      - diagnostic
+      - style
+      - performance
+
+issues:
+  exclude-rules:
+    - path: _test\.go
+      linters:
+        - unparam
+    # IATA codes are not misspellings
+    - path: codes/iata\.go
+      linters:
+        - misspell