Bump versions and binary build changes

- Go version 1.15
- Golangci-lint 1.30
- Trim path of binary built

Dockerfile

@@ -1,10 +1,10 @@
 ARG ALPINE_VERSION=3.12
-ARG GO_VERSION=1.14
+ARG GO_VERSION=1.15
 
 FROM golang:${GO_VERSION}-alpine${ALPINE_VERSION} AS builder
 RUN apk --update add git
 ENV CGO_ENABLED=0
-ARG GOLANGCI_LINT_VERSION=v1.27.0
+ARG GOLANGCI_LINT_VERSION=v1.30.0
 RUN wget -O- -nv https://raw.githubusercontent.com/golangci/golangci-lint/master/install.sh | sh -s ${GOLANGCI_LINT_VERSION}
 WORKDIR /tmp/gobuild
 COPY .golangci.yml .
@@ -14,7 +14,7 @@ COPY cmd/gluetun/main.go .
 COPY internal/ ./internal/
 RUN go test ./...
 RUN golangci-lint run --timeout=10m
-RUN go build -ldflags="-s -w" -o entrypoint main.go
+RUN go build -trimpath -ldflags="-s -w" -o entrypoint main.go
 
 FROM alpine:${ALPINE_VERSION}
 ARG VERSION
@@ -101,8 +101,6 @@ ENTRYPOINT ["/entrypoint"]
 EXPOSE 8000/tcp 8888/tcp 8388/tcp 8388/udp
 HEALTHCHECK --interval=10m --timeout=10s --start-period=30s --retries=2 CMD /entrypoint healthcheck
 RUN apk add -q --progress --no-cache --update openvpn ca-certificates iptables ip6tables unbound tinyproxy tzdata && \
-    echo "http://nl.alpinelinux.org/alpine/edge/testing" >> /etc/apk/repositories && \
-    apk add -q --progress --no-cache --update shadowsocks-libev && \
     rm -rf /var/cache/apk/* /etc/unbound/* /usr/sbin/unbound-* /etc/tinyproxy/tinyproxy.conf && \
     deluser openvpn && \
     deluser tinyproxy && \