Failing test on non x86 architectures

Hi @schollz

Thanks for your work on progressbar :)
However, while running tests on !x86 architectures, one of the test fails -- in particular this one:

=== RUN   ExampleOptionSetRenderBlankState
--- FAIL: ExampleOptionSetRenderBlankState (0.00s)
got:
0% |          |  [0s:-1s]
want:
0% |          |  [0s:0s]

On investigating further, it seems that the value of rightBrac is turning out to be negative. On further investigation, it is found that the value of the averageRate variable is "0" for this particular test, and hence a division by 0 is happening there, which results in a +Inf, now the rest of the operations convert this into 0s on x86 and -1 on rest arches.

Here's a sample code for instance:

package main

import
	(
		"time"
		"fmt"
	);

func main() {
	var rate float64 = 0
	max := 10
	min := 0
	res:= (time.Duration((1 / rate)*(float64(max) - float64(min))) * time.Second).String()
	fmt.Println(res)
}

Output on x86: 0s
Output on arm64/other arches: -1s

For now, I've applied this patch to force a 0s value if rightBrac is 0s:

--- a/progressbar.go
+++ b/progressbar.go
@@ -730,6 +730,11 @@
 	if c.predictTime {
 		leftBrac = (time.Duration(time.Since(s.startTime).Seconds()) * time.Second).String()
 		rightBrac = (time.Duration((1/averageRate)*(float64(c.max)-float64(s.currentNum))) * time.Second).String()
+		zerosec, _ := time.ParseDuration("0s")
+		rightsec, _ := time.ParseDuration(rightBrac)
+		if rightsec.Seconds() < zerosec.Seconds() {
+			rightBrac = "0s"
+		}
 	}
 
 	if c.fullWidth && !c.ignoreLength {

But I admit this might not be the best way to get around it. Please consider fixing this

Start with progressbar.go around line 732 and run the ExampleOptionSetRenderBlankState test on a non-x86 architecture to reproduce the differing output. Trace the averageRate and rightBrac values involved in the predicted time calculation; done means the test consistently reports 0s rather than -1s across architectures.