Kubernetes-dashboard: refactor Dockerfile for Trivy installation method

- Updated the Dockerfile to install Trivy using a script from the official repository, improving the installation process and reducing reliance on temporary files.
- Removed the previous method of downloading and extracting the Trivy binary, streamlining the setup.

Signed-off-by: NotHarshhaa <reddyharshhaa12@gmail.com>

Author: NotHarshhaa

Dockerfile

@@ -19,11 +19,12 @@ RUN apt-get update && apt-get install -y \
     && rm -rf /var/lib/apt/lists/*
 
 # Install Trivy for security scanning
-RUN wget -qO /tmp/trivy.tar.gz https://github.com/aquasecurity/trivy/releases/latest/download/trivy_linux_amd64.tar.gz \
-    && tar -xzf /tmp/trivy.tar.gz -C /tmp/ \
+RUN TRIVY_VERSION=$(curl -s https://api.github.com/repos/aquasecurity/trivy/releases/latest | grep '"tag_name":' | cut -d '"' -f 4) \
+    && wget -qO /tmp/trivy_${TRIVY_VERSION}_linux_amd64.tar.gz https://github.com/aquasecurity/trivy/releases/download/trivy_${TRIVY_VERSION}_linux_amd64.tar.gz \
+    && tar -xzf /tmp/trivy_${TRIVY_VERSION}_linux_amd64.tar.gz -C /tmp/ \
     && mv /tmp/trivy /usr/local/bin/trivy \
     && chmod +x /usr/local/bin/trivy \
-    && rm -f /tmp/trivy.tar.gz
+    && rm -f /tmp/trivy_${TRIVY_VERSION}_linux_amd64.tar.gz
 
 # Copy requirements first for better caching
 COPY requirements.txt .