WIP: Add tests for attachments (#116)

* Add tests for attachments

* Fix CI

* Use go 1.15 for mobile

.github/workflows/android.yml

@@ -20,7 +20,7 @@ jobs:
     - name: Set up Go 1.15
       uses: actions/setup-go@v2
       with:
-        go-version: ^1.15.6
+        go-version: ~1.15.6
       id: go
 
     - name: Checkout

.github/workflows/go.yml

@@ -16,7 +16,7 @@ jobs:
     - name: Set up Go 1.x
       uses: actions/setup-go@v2
       with:
-        go-version: ^1.13
+        go-version: ^1.16
       id: go
 
     - name: Check out code into the Go module directory
@@ -29,7 +29,7 @@ jobs:
             curl https://raw.githubusercontent.com/golang/dep/master/install.sh | sh
             dep ensure
         fi
-        go install github.com/golangci/golangci-lint/cmd/golangci-lint
+        go get github.com/golangci/golangci-lint/cmd/golangci-lint
 
     - name: Test
       run: go test -v -race ./...

.github/workflows/ios.yml

@@ -21,7 +21,7 @@ jobs:
       - name: Set up Go 1.15
         uses: actions/setup-go@v2
         with:
-          go-version: ^1.15.6
+          go-version: ~1.15.6
         id: go
 
       - name: Checkout