Calculate the standard cell potential ($E^\circ_{cell}$) for a galvanic cell composed of Zinc ($Zn$) and Copper ($Cu$). Standard reduction potentials: $Zn^{2+} + 2e^- \rightarrow Zn(s)$ ($E^\circ = -0.76 \, \text{V}$) $Cu^{2+} + 2e^- \rightarrow Cu(s)$ ($E^\circ = +0.34 \, \text{V}$)