Stelco Loses Contract to Supply GM Steel  VANCOUVER, British Columbia (Reuters) - Stelco Inc.  &lt;A HREF="http://www.investor.reuters.com/FullQuote.aspx?ticker=STEa.TO target=/stocks/quickinfo/fullquote"&gt;STEa.TO&lt;/A&gt; has lost a contract to supply steel to General Motors  Inc. &lt;A HREF="http://www.investor.reuters.com/FullQuote.aspx?ticker=GM.N target=/stocks/quickinfo/fullquote"&gt;GM.N&lt;/A&gt;, its biggest customer, because the insolvent  Canadian steelmaker failed to strike a deal with its workers,  the union at Stelco said on Monday.