Patch Dockerfile used in tests with build deps

Signed-off-by: Hidde Beydals <hello@hidde.co>

Author: hiddeco

.github/actions/run-tests/Dockerfile

@@ -1,14 +1,16 @@
 FROM golang:1.16-buster as builder
 
-# Up-to-date libgit2 dependencies are only available in
-# unstable, as libssh2 in testing/bullseye has been linked
-# against gcrypt which causes issues with PKCS* formats.
-# Ref: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=668271
-RUN echo "deb http://deb.debian.org/debian unstable main" >> /etc/apt/sources.list \
-    && echo "deb-src http://deb.debian.org/debian unstable main" >> /etc/apt/sources.list
+# Build dependencies
 RUN set -eux; \
-    apt-get update \
-    && apt-get install -y libgit2-dev/unstable \
+    apt-get update && \
+    apt-get install -y \
+        cmake \
+        curl \
+        gcc \
+        libc6-dev \
+        make \
+        pkg-config \
+        python3 \
     && apt-get clean \
     && apt-get autoremove --purge -y \
     && rm -rf /var/lib/apt/lists/*