[BUG] arm64: bad kubectl binary

[disconn3ct]

Describe the bug
Using ghcr.io/infracloudio/botkube:v0.12.2, commands on arm64 return fork/exec /usr/local/bin/kubectl: exec format error

To Reproduce
Steps to reproduce the behavior:

1. Install botkube on arm64
2. Send a command (botkube cluster-info)
3. See error: fork/exec /usr/local/bin/kubectl: exec format error

Expected behavior
Kubectl uses the correct architecture

Screenshots
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Additional context
Add any other context about the problem here.

[disconn3ct]

I'll try to get time this evening to send a pull but in short, it can be fixed by changing line 30 from bitnami to:

# Download the latest kubectl in the appropriate architecture. Currently handles aarch64 (arm64) and x86_64 (amd64).
RUN MACH=$(uname -m); if [[ ${MACH} == "aarch64" ]]; then ARCH=arm64; \
    elif [[ ${MACH} == "x86_64" ]]; then ARCH=amd64; \
    else echo "Unsupported arch: ${MACH}"; ARCH=${MACH}; fi; \
    wget -O /usr/local/bin/kubectl "https://dl.k8s.io/release/$(wget -qO - https://dl.k8s.io/release/stable.txt)/bin/linux/${ARCH}/kubectl" && \
    chmod +x /usr/local/bin/kubectl

[PrasadG193]

@disconn3ct we can do a quick release if you could fix this. Please let me know if I can help